update in avi/openDML muxer

[mean]

The avi/opendML muxer had been cleaned up, but it is still work in progress
What works :
=========
* Type 1 avi, type 2 Avi
* >  4 GB type2 plays on linux

What does not work :
================
* Auto switch from type 1 to type2
* > 4 GB does not seem  to be liked by WMP

[mean]

> 4GB files seems ok, at least with vlc

Win7' s windows media player does not seem to like the file, but it also fails playing from vdub

[mean]

Should work mostly fine starting from r8108