libavsmash: Support '2vuy' and 'yuv2'.
libavsmash: Fix implicit declaration of function 'av_realloc' for libav.
lsmashinput: Cosmetics about Libav video handler.
lsmashinput: Cosmetics about Libav audio handler.
lsmashinput: Cosmetics around Libav indexer.
lsmashsource: Split some codes into files.
lsmashinput: Split some codes of Libav reader into files.
Move common basic functions into common/utils.c/h.
lsmashsource: Add LWLibavVideoSource() and LWLibavAudioSource().
lsmashsource: For LWLibavSource, rename 'track' into 'stream_index'.
vslsmas: Add LWLibavSource().

Rename Source() into LibavSMASHSource().
lsmashsource: Fix some memory leaks in LW-Libav reader.
lsmashsource: Fix .lwi file generation option.
lwlibav: Fix 10L in 3bde4e905d .
Integrate video output handler.
Integrate audio output handler partially.
lsmashsource: Add 'av_sync' option to LWLibavAudioSource().

If true, activate AV synchronization against the active video stream in the same index file.
Note: its default value is false.
lsmashsource: Avoid calling scaler if not needed.
lsmashsource: Stop using temporary buffer for scaling.
lsmashsource: Use sws_scale() instead of env->BitBlt even if there is no pixel format conversion.