-Add PacketFactory class to instantiate Packet objects. PacketFactory internally contains a memory pool of Packet objects and returns a pointer to an unused instantiation when createPacket is called.

git-svn-id: http://odamex.net/svn/root/branches/net3-base@4583 b0bcef46-2027-0410-bd56-ab726e9a1d04
-Revert r4571. BitStreams will typically be stored inside of Packets so there is no need for reference counting them.

git-svn-id: http://odamex.net/svn/root/branches/net3-base@4585 b0bcef46-2027-0410-bd56-ab726e9a1d04