diff --git a/.editorconfig b/.editorconfig
index 890c954e15..498a818f87 100644
--- a/.editorconfig
+++ b/.editorconfig
@@ -4,7 +4,7 @@ root = true
 charset = utf-8
 end_of_line = lf
 indent_style = tab
-insert_final_newline = false
+insert_final_newline = true
 trim_trailing_whitespace = true
 
 [**.{jshintrc,json,neon,scss-lint,yml}]
diff --git a/.stylelintrc b/.stylelintrc
index 8f1de4982b..f7135165f7 100644
--- a/.stylelintrc
+++ b/.stylelintrc
@@ -1,5 +1,5 @@
 {
-"extends": "@the-events-calendar/product-taskmaster/config/stylelint",
+	"extends": "@the-events-calendar/product-taskmaster/config/stylelint",
 	"rules": {
 		"property-no-unknown": [
 			true, {
diff --git a/bin/ModifiedSemverVersioning.php b/bin/ModifiedSemverVersioning.php
new file mode 100644
index 0000000000..c77e7ba070
--- /dev/null
+++ b/bin/ModifiedSemverVersioning.php
@@ -0,0 +1,269 @@
+<?php // phpcs:ignoreFile StellarWP.Classes.ValidClassName.NotSnakeCaseClass
+/**
+ * Modified Semver versioning plugin.
+ *
+ * Allows for x.y.z.T where T is a hotfix version
+ *
+ * @package TEC\Actions\Changelogger
+ */
+
+namespace TEC\Actions\Changelogger\Plugins;
+
+use Automattic\Jetpack\Changelog\ChangeEntry;
+use Automattic\Jetpack\Changelogger\PluginTrait;
+use Automattic\Jetpack\Changelogger\VersioningPlugin;
+use InvalidArgumentException;
+
+/**
+ * ModifiedSemver versioning plugin.
+ *
+ * Allows for x.y.z.T where T is a hotfix version
+ */
+class ModifiedSemverVersioning implements VersioningPlugin {
+	use PluginTrait;
+
+	/**
+	 * Parse a semver version.
+	 *
+	 * @param string $version Version.
+	 * @return array With components:
+	 *  - major: (int) Major version.
+	 *  - minor: (int) Minor version.
+	 *  - patch: (int) Patch version.
+	 *  - hotfix: (?int) Hotfix version.
+	 *  - version: (string) Major.minor.patch.
+	 *  - prerelease: (string|null) Pre-release string.
+	 *  - buildinfo: (string|null) Build metadata string.
+	 * @throws InvalidArgumentException If the version number is not in a recognized format.
+	 */
+	public function parseVersion( $version ) {
+		// This is slightly looser than the official version from semver.org, in that leading zeros are allowed.
+		if ( ! preg_match( '/^(?P<major>\d+)\.(?P<minor>\d+)\.(?P<patch>\d+)(?:\.(?P<hotfix>\d+))?(?:-(?P<prerelease>(?:[0-9a-zA-Z-]+)(?:\.(?:[0-9a-zA-Z-]+))*))?(?:\+(?P<buildinfo>[0-9a-zA-Z-]+(?:\.[0-9a-zA-Z-]+)*))?$/', $version, $m ) ) {
+			throw new InvalidArgumentException( "Version number \"$version\" is not in a recognized format." );
+		}
+		$info = [
+			'major'      => (int) $m['major'],
+			'minor'      => (int) $m['minor'],
+			'patch'      => (int) $m['patch'],
+			'hotfix'     => isset( $m['hotfix'] ) && '' !== $m['hotfix'] ? (int) $m['hotfix'] : null,
+			'version'    => sprintf( '%d.%d.%d', $m['major'], $m['minor'], $m['patch'] ) . ( ! empty( $m['hotfix'] ) ? '.' . (int) $m['hotfix'] : '' ),
+			'prerelease' => isset( $m['prerelease'] ) && '' !== $m['prerelease'] ? $m['prerelease'] : null,
+			'buildinfo'  => isset( $m['buildinfo'] ) && '' !== $m['buildinfo'] ? $m['buildinfo'] : null,
+		];
+
+		if ( null !== $info['prerelease'] ) {
+			$sep        = '';
+			$prerelease = '';
+			foreach ( explode( '.', $info['prerelease'] ) as $part ) {
+				if ( ctype_digit( $part ) ) {
+					$part = (int) $part;
+				}
+				$prerelease .= $sep . $part;
+				$sep         = '.';
+			}
+			$info['prerelease'] = $prerelease;
+		}
+
+		return $info;
+	}
+
+	/**
+	 * Check and normalize a version number.
+	 *
+	 * @param string|array $version Version string, or array as from `parseVersion()` (ignoring a `version` key).
+	 * @param array        $extra Extra components for the version, replacing any in `$version`.
+	 * @return string Normalized version.
+	 * @throws InvalidArgumentException If the version number is not in a recognized format or extra is invalid.
+	 */
+	public function normalizeVersion( $version, $extra = [] ) {
+		if ( is_array( $version ) ) {
+			$info = $version + [
+					'prerelease' => null,
+					'buildinfo'  => null,
+				];
+			$test = $this->parseVersion( '0.0.0' );
+			unset( $test['version'] );
+			if ( array_intersect_key( $test, $info ) !== $test ) {
+				throw new InvalidArgumentException( 'Version array is not in a recognized format.' );
+			}
+
+			if ( null !== $info['prerelease'] ) {
+				$info['prerelease'] = $this->parseVersion( '0.0.0-' . $info['prerelease'] )['prerelease'];
+			}
+		} else {
+			$info = $this->parseVersion( $version );
+		}
+		$info = array_merge( $info, $this->validateExtra( $extra, false ) );
+
+		$ret = sprintf( '%d.%d.%d', $info['major'], $info['minor'], $info['patch'] ) . ( ! empty( $info['hotfix'] ) ? '.' . (int) $info['hotfix'] : '' );
+		if ( null !== $info['prerelease'] ) {
+			$ret .= '-' . $info['prerelease'];
+		}
+		if ( null !== $info['buildinfo'] ) {
+			$ret .= '+' . $info['buildinfo'];
+		}
+		return $ret;
+	}
+
+	/**
+	 * Validate an `$extra` array.
+	 *
+	 * @param array $extra Extra components for the version. See `nextVersion()`.
+	 * @param bool  $nulls Return nulls for unset fields.
+	 * @return array
+	 * @throws InvalidArgumentException If the `$extra` data is invalid.
+	 */
+	private function validateExtra( array $extra, $nulls = true ) {
+		$info = [];
+
+		if ( isset( $extra['prerelease'] ) ) {
+			try {
+				$info['prerelease'] = $this->parseVersion( '0.0.0-' . $extra['prerelease'] )['prerelease'];
+			} catch ( InvalidArgumentException $ex ) {
+				throw new InvalidArgumentException( 'Invalid prerelease data' );
+			}
+		} elseif ( $nulls || array_key_exists( 'prerelease', $extra ) ) {
+			$info['prerelease'] = null;
+		}
+		if ( isset( $extra['buildinfo'] ) ) {
+			try {
+				$info['buildinfo'] = $this->parseVersion( '0.0.0+' . $extra['buildinfo'] )['buildinfo'];
+			} catch ( InvalidArgumentException $ex ) {
+				throw new InvalidArgumentException( 'Invalid buildinfo data' );
+			}
+		} elseif ( $nulls || array_key_exists( 'buildinfo', $extra ) ) {
+			$info['buildinfo'] = null;
+		}
+
+		return $info;
+	}
+
+	/**
+	 * Determine the next version given a current version and a set of changes.
+	 *
+	 * @param string        $version Current version.
+	 * @param ChangeEntry[] $changes Changes.
+	 * @param array         $extra Extra components for the version.
+	 *  - prerelease: (string|null) Prerelease version, e.g. "dev", "alpha", or "beta", if any. See semver docs for accepted values.
+	 *  - buildinfo: (string|null) Build info, if any. See semver docs for accepted values.
+	 * @return string
+	 * @throws InvalidArgumentException If the version number is not in a recognized format, or other arguments are invalid.
+	 */
+	public function nextVersion( $version, array $changes, array $extra = [] ) {
+		$info = array_merge(
+			$this->parseVersion( $version ),
+			$this->validateExtra( $extra )
+		);
+
+		$significances = [];
+		foreach ( $changes as $change ) {
+			$significances[ (string) $change->getSignificance() ] = true;
+		}
+		if ( isset( $significances['major'] ) ) {
+			$info['patch'] = 0;
+			if ( 0 === (int) $info['major'] ) {
+				if ( is_callable( [ $this->output, 'getErrorOutput' ] ) ) { // @phan-suppress-current-line PhanUndeclaredMethodInCallable -- See https://github.com/phan/phan/issues/1204.
+					$out = $this->output->getErrorOutput(); // @phan-suppress-current-line PhanUndeclaredMethod -- See https://github.com/phan/phan/issues/1204.
+					$out->writeln( '<warning>Semver does not automatically move version 0.y.z to 1.0.0.</>' );
+					$out->writeln( '<warning>You will have to do that manually when you\'re ready for the first release.</>' );
+				}
+				++$info['minor'];
+			} else {
+				$info['minor'] = 0;
+				++$info['major'];
+			}
+		} elseif ( isset( $significances['minor'] ) ) {
+			$info['patch'] = 0;
+			++$info['minor'];
+		} else {
+			++$info['patch'];
+		}
+
+		return $this->normalizeVersion( $info );
+	}
+
+	/**
+	 * Compare two version numbers.
+	 *
+	 * @param string $a First version.
+	 * @param string $b Second version.
+	 * @return int Less than, equal to, or greater than 0 depending on whether `$a` is less than, equal to, or greater than `$b`.
+	 * @throws InvalidArgumentException If the version numbers are not in a recognized format.
+	 */
+	public function compareVersions( $a, $b ) {
+		$aa = $this->parseVersion( $a );
+		$bb = $this->parseVersion( $b );
+		if ( $aa['major'] !== $bb['major'] ) {
+			return $aa['major'] - $bb['major'];
+		}
+		if ( $aa['minor'] !== $bb['minor'] ) {
+			return $aa['minor'] - $bb['minor'];
+		}
+		if ( $aa['patch'] !== $bb['patch'] ) {
+			return $aa['patch'] - $bb['patch'];
+		}
+
+		if ( ! empty( $aa['hotfix'] ) || ! empty( $bb['hotfix'] ) ) {
+			if ( empty( $aa['hotfix'] ) ) {
+				return -1 * $bb['hotfix'];
+			}
+			if ( empty( $bb['hotfix'] ) ) {
+				return $aa['hotfix'];
+			}
+
+			if ( $aa['hotfix'] !== $bb['hotfix'] ) {
+				return $aa['hotfix'] - $bb['hotfix'];
+			}
+		}
+
+		if ( null === $aa['prerelease'] ) {
+			return null === $bb['prerelease'] ? 0 : 1;
+		}
+		if ( null === $bb['prerelease'] ) {
+			return -1;
+		}
+
+		$aaa = explode( '.', $aa['prerelease'] );
+		$bbb = explode( '.', $bb['prerelease'] );
+		$al  = count( $aaa );
+		$bl  = count( $bbb );
+		for ( $i = 0; $i < $al && $i < $bl; $i++ ) {
+			$a = $aaa[ $i ];
+			$b = $bbb[ $i ];
+			if ( ctype_digit( $a ) ) {
+				if ( ctype_digit( $b ) ) {
+					if ( (int) $a !== (int) $b ) {
+						return (int) $a - (int) $b;
+					}
+				} else {
+					return -1;
+				}
+			} elseif ( ctype_digit( $b ) ) {
+				return 1;
+			} else {
+				$tmp = strcmp( $a, $b );
+				if ( 0 !== $tmp ) {
+					return $tmp;
+				}
+			}
+		}
+		return $al - $bl;
+	}
+
+	/**
+	 * Return a valid "first" version number.
+	 *
+	 * @param array $extra Extra components for the version, as for `nextVersion()`.
+	 * @return string
+	 */
+	public function firstVersion( array $extra = [] ) {
+		return $this->normalizeVersion(
+			[
+				'major'  => 0,
+				'minor'  => 1,
+				'patch'  => 0,
+				'hotfix' => null,
+			] + $this->validateExtra( $extra )
+		);
+	}
+}
diff --git a/common b/common
index 68845e726e..75a6ef1a0b 160000
--- a/common
+++ b/common
@@ -1 +1 @@
-Subproject commit 68845e726e47f216a5139a52996a5df1b2e4d59d
+Subproject commit 75a6ef1a0bcf93f279c744763e4d12785284e9de