TODO: Fix crash when closing sink window while stream is paused

# Conflicts:
#	src/CMakeLists.txt
#	src/GUI/WindowCloseEventFilter.cpp
#	test/CMakeLists.txt

 - bugs: access to empty var

it seems like the transcoder is not running at all
 - check the transcoder setup and compare to simpletranscode example

Added instant response on rejecting data connection request and fixed bug with resuming listening for connection in NetworkSinkHandler

 - dblclick on playback window toggles fullscreen

 - closing application terminates StreamThread and NetworkSinkHandler gracefully