Fix: Possible double free when resetting PGS subtitles.

This resulted in random crashes when seeking quickly in a file with PGS subtitles and other various cases.

Fixes #4240.
Update translations from Transifex:

 - Catalan
 - Croatian
 - Japanese
 - Slovenian
 - Spanish

Fixes #4268.
StatusLabel: flickerless paint
PlaylistBar: drag and drop deeply nested folders

Support it.
Discard .ini cache when it's not being accessed

Refs #4193
Flush .ini cache after idle processing is done
Use the right prefix for bool variable
FileAssoc: don't use static methods
FileAssoc: don't use static variables
Construct CAppSettings in InitInstance()

It allows us to use COM objects in CAppSettings ctor.
Reduce header dependencies
Cosmetics

Placed 'extern' functions together.
Marked local functions as 'static'.
And some minor clean-ups and cosmetics.
Use 'override' keyword
A bit more sane hooks declaration
Simplify setting heap information