VMROSD: Show chapter marks on OSD seekbar.
VMROSD: Invalidate the OSD when the position is updated while the seekbar is visible.

This makes sure the user can actually see the cursor moving while playing.
VMROSD: Increase seekbar cursor accuracy.
MediaInfo: Enable image formats.
Update coverity.bat.

Redirect stdout to stderr and both to NUL for the tar check.
Update Unrar to 5.0.8.
MediaFormats: Add an abbreviated extension list to the Media files and Audio files filters when hide extensions is disabled.

This prevents an otherwise huge list from being added to the filter name.
MediaFormats: Add Material Exchange Format.
This commit fixes ticket #800.