Update SoundTouch to v1.8.0 r201.
Initialize variables.
Update unrar to v5.2.3.
Installer: update Arabic translation.
Updated LAV Filters to 0.63-24-240f579 (custom build based on 0.63-18-de098da).

Important changes:
 - LAV Video Decoder: Fix a crash related to DVD subs (fixes #5522) (regression from 73d3cab944635944d6d0034376c743798ee5bdd8).
 - LAV Audio Decoder: Fix a possible crash when seeking (fixes #5523) (regression from 73d3cab944635944d6d0034376c743798ee5bdd8).
 - LAV Audio Decoder: Switch to native FFmpeg decoder for Opus.
 - Update FFmpeg library.
Update translations from Transifex:

 - Arabic
 - Catalan
 - Japanese
 - Portuguese (Brazil)
 - Russian
 - Swedish
 - Turkish
Add more variables to the variables.html.
CWebClientSocket: Replace new variables and deduplicate code a little.

Closes #134
wip