As https://gerrit.wikimedia.org/r/c/mediawiki/skins/BlueSky/+/647359 points out, many skins now only require a single PHP file if using a BaseTemplate
- The Skin class should not need to define $this->stylename . This should be handled in the constructor and/or inside SkinFactory. It can be derived from name
- It should be possible to set the name of the PHP class using template option. Note in SkinMustache this is the path to a Mustache file, but here it would be the name of the PHP class.