Implements more aggressive dropping of RTP packets in case the respective RTP packet queue is full in order to increase the chances of decreasing the drop rate over time and, consequently, bettering the audio quality. Extracts the RTP packet queue statistics into their own class as a first step in refactorying the RTP packet queue/jitter buffer implementations for the purposes of reducing code complexity.

git-svn-id: http://svn.code.sf.net/p/fmj/code/fmj@27 799b4810-d841-4bb4-a54b-9156a0c3e4cd