Nightly to fix some issues on 2.7.2

[mean]

That version should fix some of 2.7.2 VC++ issues :
http://avidemux.org/nightly/vsWin64/Avidemux_2.7.2%20VC++%2064bits%20190318.exe

In particular :
* PNG loading fixed
* No more nagging screen about vsscript.dll missing if you dont have vapoursynth installed
* Fixed auto save when crashing
* WMV/ASF demuxing

So it *should* be better
There is still a known BMP decoding bug being ironed out

[mean]

New nightly at 5pm, contains one additional fix (autosave on crash)

[fish]

Thank you, much appreciated.