Fixes the following problems.
A malicious client was able to contact another peer faking its identity
(even looking like he was the server).
A malicious client was able to force other client disconnections by sending
bogus system packets to the server.
NetworkedMultiplayerENet::get_packet was reporting the wrong size for the packet buffer exposing a potential buffer overflow in case of malformed/malicious packets
-Ability to set compression to ENet packets (check API)
-Fixed small bug in StringDB that lead to duplicate empty strings
-Added a new class, StreamPeerBuffer, useful to create your own tightly packed data
For reference, when you include a Windows header (be it directly windows.h or something that includes it)
put it at the end of the includes. it seems I forgot.
