* When loading footprint do not retest every footprint in cache.  Only test
  the footprint being loaded.  Fixes long load times on libraries with a lot
  of parts.
* Fix footprint name bug where file extension was added to the end of the
  footprint name.
* Fix bug in path equivalence test due to Posix path separators in footprint
  library table.  Convert paths to native separator before comparison.
* Fix a bug in FOOTPRINT_VIEWER_FRAME::OnActivate() which cause the footprint
  list to always get reloaded when using footprint library tables.
* Remove some unnecessary debugging messages.
* Add a few Doxygen comments to FP_CACHE in kicad_plugin.cpp.