More lang variant stuff:

More lang variant stuff:
* More parser tests, also added 'variant' option for testing
* Add global $wgDefaultLanguageVariant, can be used to set a default
  fallback variant
* Restructured some of the parser code in LanguageConverter, fix flag
  processing and add some comments to despookify the old zh code :)
* Cleanup of some old hacks in LanguageSr and Kk (do not use the global
  title object, but the one passed to the parser)