Preferences as Plain Text and Compatibility Support

Updating blender is an act of faith, faith that your hard built preferences in userpref and startup blends work correctly. I think we can try to deal with blender preferences and make them first plain text (ini, css, xml, yml), and second separated from the blend file format, which I think should also be plain text (think Maya Ascii .ma) for debug purposes. Add also a compatibility layer support that warns you on mismatches so unsupported settings don't pass unnoticed.