Adds an RTP timestamp field to Buffer.

git-svn-id: http://svn.code.sf.net/p/fmj/code/fmj@43 799b4810-d841-4bb4-a54b-9156a0c3e4cd
Reverts r40.

git-svn-id: http://svn.code.sf.net/p/fmj/code/fmj@44 799b4810-d841-4bb4-a54b-9156a0c3e4cd
Fixes a bug which caused the interval for timing out an SSRC to grow, resulting
in streams not being timed out in some situations.

git-svn-id: http://svn.code.sf.net/p/fmj/code/fmj@45 799b4810-d841-4bb4-a54b-9156a0c3e4cd