add XV renderer. TODO: ImageConverter should output yuv data
initialize xvimage. use ugly rgb->yuv in XVRenderer

performance is bad now
Merge branch 'master' into x11
force recheck if FFmpeg not detected

TODO: should we only recheck the part not pass the test?
fix qmake warning for back slash.

a back slash is '\\' for qmake
Add missing config test
Merge branch 'master' into x11

Conflicts:
	QtAV.pro
xv: black background
Merge branch 'x11'
qmake: correct Qt version detection. do not empty cache if recheck
gl: check gl1 support
do not add qt opengl module if gl test failed
Merge branch 'gl'
README: building, player usage, FFmpeg projects etc
gl: do not include GLWidgetRenderer.h if gl is disabled

link error with msvc. why gcc is ok?
README: building QtAV
Fix compile warning about size_t
fix debug linking

the debug library name is wrong. why i commented that line before?
update documents about building. add a Chinese document
d2d: some toolchains need _COM_interface definition