AVC/h.264 common: refactor timestamping code
AVC/h.264: only forcefully flag the very first frame as an I frame
AVC/h.264 common: refactor timestamping code
mkvinfo: report picture type based on number of references, not on their value
cosmetics: alignment
mkvextract: don't write BOMs for non-UTF locales

Fixes #1086.
Merge branch 'avc-fix-buffering'

Conflicts:
	ChangeLog