Update translations from Transifex:

 - Arabic
 - Chinese (Simplified)
 - Croatian
 - Czech
 - French
 - Galician
 - German
 - Greek
 - Japanese
 - Malay
 - Polish
 - Portuguese (Brazil)
 - Slovenian
 - Spanish
 - Swedish
 - Thai
 - Turkish
 - Vietnamese
Fix a preposition mistake in the English translation.
LAV Filters: Distribute CHANGELOG.txt, README.txt, COPYING files (PoC).
Don't force any background color for the Shockwave graph.

This commit fixes #1747.
WebUI: Inform the web interface that no audio stream is available.
WebUI: Make use of new [hasaudio] info.
What the hell was intended here?!

Trying to make some sense of that code. Without much luck so far...