fix bug - cerr missing flush
add functions in VideoInfoDumper.py

1. VideoInfoDumper.py can dump infomation of all the meida files in a folder
2. add clear in Makefile
change libav to ffmpeg
videoinfodumper with ffmpeg lib
add "default samples & get time" in AudioPlayer

1. fill default samples in the buffer ( for debug )
2. add time request function
fix compile warning
replace qt audio with portaudio

1. add fillDefaultSample in AudioPlayer
2. fix get time bug in AudioPlayer
3. now start to play a/v when some decoded a/v frames are ready
add get bytes function if FrameFifo
fix compile warning
Weird bug exsit: invalid parameter ...

invalid parameter Invalid parameter passed to C runtime
seem to clean the weird bug, but don't know why
fix seek bug when using portaudio

1. fix seek bug when using portaudio
2. initialize mAudioPlayer with null in MultimediaWidget
3. rewrite some comments
Merge branch 'use_portaudio' into develop

Conflicts:
	AudioPlayer/AudioPlayer.cpp
Reduce memory usage! 2xxMB => 55MB

and I thought the bug of "invalid paremeter in runtime..." is caused by
memory used up.
try fix sync but fail
add debug buffer in AudioPlayer

mPlayStream save the stream which portaudio playing ( callback write )
mWriteStream save the stream which pushed by the user of AudioPlayer ( not
implemted )

the debug buffer is used to dump the stream which portaudio playing
for the time being, the ~AudioPlayer is not called correctly

if you want to dump mPlayStream, please add codes manually
Fix sync bug!
remove qt audio device code
add buffer latency in AudioPlayer
fix open file bug