Fix: DVD subtitles were always re-enabled when clicking on a menu entry related to external subtitles.

This commit fixes #4141.
Rename "Enabled" menu entry to "Enable DVD subtitles" for clarity.

This commit fixes #4141.
Lite builds: Fix a minor inconsistency regarding the output directory.

Lite debug builds use "mpc-hc_x??_Debug Lite" while release builds always used "mpc-hc_x??" for both normal and lite builds.
Fix: x86 and x64 versions conflicted over file associations.

4f465cf8b81f1da800b1bfc57cc48e317d24fbb5 was incomplete for Vista+.

This commit fixes #4064.
Language menu: Ensure "Language" always appears in English in menu entry.

If "Language" doesn't appear in the translated string, "(Language)" will be appended automatically.