png prelaminary testing

[Jan Gruuthuse]

1280x720 png:


Test:
png to 1 second mkv video:
------------------------------
load png into avidemux
look at time index changed to [00:00:00.040]
copy [Ctrl] [C]
paste [Ctrl] [V]
until time index is about the time you want
[00:00:01.000]

not working:
- FLV1 (flash)
- Mjpeg Encoder
- mpeg2 (ff)
- Mpeg4 ASP(ff)
- MPEG4 AVC(x264)

working:
- (FF)HuffYUV
- HEVC (x265)
- Mpeg4ASP (xvid4)
- Nvidia h264
- Nvidia HEVC

not tested/clear how to use
- YV12 Encoder
- png encoder