Quick fix for Window Capture

I'm not quite sure why anyone would ever want the Window Capture to turn
into a giant black rectangle just because the window being captured was
closed.
force MP3 to always use 44.1khz to prevent transmission from breaking
Merge branch 'master' of https://github.com/jp9000/OBS
Fixed string length for GetPathDirectory
Fixed DateTimeName for .flv output

Also works with directory names containing dots (see <http://obsproject.com/forum/viewtopic.php?f=6&t=8967>)
Added h264 main profile override to QSV encoder
DirectShow global source audio fix

Make it so that global DirectShow sources actually mute themselves when
you switch to a scene where they're not present again.
DirectShow global source audio fix round 2

One more fix, because people sometimes apparently add the same global
video capture device source to the same scene twice.