MPCVideoDec: fixed playback h264 after "stop" on Intel HD Graphics (force recreate dxva decoder).
(thanks to Aleksoid1978)
Updated Basque translation.

Refs: #2890.
Add the "AVI/WAV File Source" to the source filters list.
Subtitles: Make both DVD subtitles show in case of overlap

Makes behavior consistent with VLC and mplayer/libavcodec DVD
subtitle implementations. Sets the StopTime of the subtitle
before the same as the StartTime of the currently added DVD
subtitle.

Fixes #1392
Update Changelog.
MpaDecFilter->Mixer: fixed FlushBuffers() function
Initialize variables in the constructor.
Cppcheck fixes:

* reduce variable scope
* remove unneeded variable assignments
losslessly compress res/tickcross.png
typo