Reduced number of sender threads to 1; minor cleanup
Fixed a bug that caused lots of unnecessary mouse location updates to be sent (while not moving the mouse)
Traffic optimization that causes block updates to be held back, they're sent either when the block's content stops changing, or after a timeout (currently set to 10 screen sampling intervals, see DIRTY_COUNT_LIMIT)
Merge remote-tracking branch 'rsippl/deskshare-optimizations'
Merge branch 'master' of https://github.com/bigbluebutton/bigbluebutton