6.3.2: Anonymous child classes

• Allowed new class() extends self inside class declarations - @thekid

6.3.1: Cloning fix

• Fix being able to clone enum lookalikes - @thekid
• Fix clone operator - @thekid

6.3.0: PHP enum support

• Merged PR #106: Compile PHP enums to PHP 7/8 lookalikes, PHP 8.1 native.
  (@thekid)

6.2.0: Arbitrary expressions as initializers

• Merged PR #104: Support arbitrary expressions in property initializations
  and parameter defaults
  (@thekid)

6.1.1: Nullable types fixes

• Fixed issue #102: Call to a member function children()... - @thekid
• Fixed issue #102: PHP 8.1 compatibility - @thekid
• Fixed issue #103: Nullable types - @thekid

6.1.0: Show languages and emitters

• Included languages and emitters in xp compile output - @thekid

6.0.0: Extended match statement, annotations cleanup

• Added -q command line option which suppresses all diagnostic output
  from the compiler except for errors
  (@thekid)
• Removed support for using curly braces as offset (e.g. $value{0})
  (@thekid)
• Merged PR #92: Add support for explicit octal integer literal notation
  See https://wiki.php.net/rfc/explicit_octal_notation (PHP 8.1)
  (@thekid)
• Merged PR #93: Allow match without expression: match { ... }. See
  https://wiki.php.net/rfc/match_expression_v2#allow_dropping_true
  (@thekid)
• Removed support for legacy XP and Hack language annotations, see #86
  (@thekid)
• Merged PR #96: Enclose blocks where PHP only allows expressions. This
  not only allows fn() => { ... } but also using blocks in match.
  (@thekid)

5.7.0: Compile to XAR

• Verified full PHP 8 support now that PHP 8.0.0 has been released,
  see https://www.php.net/archive/2020.php#2020-11-26-3
  (@thekid)
• Merged PR #95: Support compiling to XAR archives - @thekid

5.6.0: PHP 8 feature completeness

• Merged PR #94: Add support for static return type - @thekid
• Optimized null-safe instance operator for PHP 8.0 - @thekid
• Added PHP 8.1-dev to test matrix now that is has been branched
  (@thekid)
• Added support for non-capturing catches, see this PHP 8 RFC:
  https://wiki.php.net/rfc/non-capturing_catches
  (@thekid)

5.5.0: Union and callable types

• Merged PR #91 - Refactor rewriting type literals:
  • Changed implementation to be easier to maintain
  • Emit function types as callable in all PHP versions
  • Emit union types as syntax in PHP 8+
    (@thekid)