MediaFormats: Add an abbreviated extension list to the Media files and Audio files filters when hide extensions is disabled.

This prevents an otherwise huge list from being added to the filter name.
Improve the infinite recursion detection when parsing playlists.

The parser was sometimes too strict and rejected valid playlists.
Audio Switcher: Exhibit all audio tracks available.

The "Play > Audio" menu now includes all the embedded tracks exhibited by the source filter and the external tracks.
Put LAVFilters files in a different folder when using x64.