CVobSubFile: Deobfuscation in ReadIdx.
Cosmetic: Use a different string for the subtitles styles menu and dialog.

This commit fixes #3731.
Make the non-system audio renderer names translatable.

Ticket #3725.
Cosmetic: Don't use spaces between slashes in internal filter names.

Ticket #3725.
Fix potential crash when reloading the subtitles.

This commit fixes #3668.
Improve the speed of subtitles toggling (on/off) and switching.

Avoid reloading the subresync bar if the same subtitles were already loaded.

This commit fixes #3650.