- Change formatting to use markdown, implements xp-framework/rfc#273
- Only add .xar and .php files to class path
- Prepare 5.9.3
- Bump version to 5.9.4-dev
- configure maven-release-plugin, so
  * branches are created and checked out locally during
    the release build
  * the tag name format is `maven-$version`
  * changes won't be pushed to upstream repository
- bump version to 5.9.4-SNAPSHOT