FORD v6.1.9

What's Changed

• Update math and environ markdown extensions by @ZedThree in #385
• External projects: deal with extended types by @haraldkl in #396
• Fix external project test by @ZedThree in #397
• Fix CSS for markdown tables and add optional striped-table extension by @ZedThree in #384
• Fix showing source in generated docs by @ZedThree in #390
• Fix type permission attributes by @ZedThree in #392
• Fix for preprocessors that can't read from stdin by @ZedThree in #393
• Fix exclude_dirs by @ZedThree in #394

Full Changelog: v6.1.8...v6.1.9