try to use swresample/avresample

convert part is not finished
Merge branch 'master' into swr

Conflicts:
	src/QtAV/QtAV_Global.h
	src/libQtAV.pro
Add seek bar for player

BUG:
parent widget's paint engine must be qpainter, otherwise children may
not update
TODO:
subclass of QSlider. press slider can not change value
auto hide slider
refine scripts code
osd: fix remaining time and total time for some media

TODO:
why AVStream.duration may be wrong?
fix compile error for vc
check vo filters size first
Merge branch 'dev'
qmake: fix compile test check
add missing return value
use VideoRenderer::handlePaintEvent() for the render logic

TODO:
1. needUpdateBackground() not virtual. use widget_holder &&
widget_hoder.rect() etc.
2. needDrawFrame() not pure, always !data.isEmpty()
3. handlePaintEvent() parameter can be empty
4. mutex scope. d2d need a larger scope
set graphicsitem filter context's painter
less warnings
reduce packet queue capacity to reduce blocking time

TODO:
videowall seems not sync well
d2d: use handlePaintEvent without crash(lock EndDraw())
OSD filter supports opacity(qpainter)
OSD(qpainter): font
add FFmpeg build script. add 'x' permission to scripts
not sure whether opengl will flicker
Merge branch 'master' into player