Update lcms2 to 4da8703.
Update .gitignore.
Update unrar to v5.1.4.

5.1.4.tar.gz - 5.10.3 in the rc file...
ISR/VSFilter: Support loading external PGS subtitles.

This commit fixes #1411.
GFN.cpp/.h: Rename the files to SubtitleHelpers.cpp/.h and cosmetics.

Add a new namespace, remove the external array, ...
Factorize the code used to guess the subtitle name and use it for external PGS subtitles.
Docs: Change the tag numbering of LAV Filters/ffmpeg.

Follow the same principle as the nightly builds numbering now that we use `git describe`.

MPC-HC 1.7.5 was a hotfix release so neither LAV Filters or ffmpeg were updated so we won't have any tag collision.
Translations: Move the language resources to their own file.
Move the UI language selection to the option dialog.

The growing number of translations makes the menu difficult to use.
UI language: Remove the resource IDs.

We don't need resource IDs anymore except to maintain compatibility with the language setting saved from really old versions (nearly two years old). The compatibility gain isn't worth the trouble so people upgrading from those old versions will now have the UI language reset to the default language based on Windows localization.
Subresync bar: Use translatable strings when possible.
Capture dialog: Split some functions and factorize some code.
Fix: The dockable bars were not updated when changing the UI language.
Use the event system to handle UI language changes.
Option dialog: Reload the dialog in case of language change.

The dialog will be closed and reopened when "Apply" is pressed if the language was changed.
Cosmetics: Fix a typo (recieves --> receives).