-Remove Connection::checkPacketType as this information is returned by Packet::getType.
-Add comments explaining the setting of mRecvSequenceValid and mLastAckSequenceValid during the Connection negotiation process.

git-svn-id: http://odamex.net/svn/root/branches/net3-base@4597 b0bcef46-2027-0410-bd56-ab726e9a1d04
-Add ConnectionStatistics class to encapsulate the calculation of network connection statistics.
-Remove the statistic-related member variables from the Connection class.
-Connection now maintains an instance of ConnectionStatistics.

git-svn-id: http://odamex.net/svn/root/branches/net3-base@4598 b0bcef46-2027-0410-bd56-ab726e9a1d04