improve comments and some code in user manager
* add possibility to add beforePacketProcess and afterPacketProcess events (test phase!)
make beforePacketProcess and afterPacketProcess events working (tests past!)
if EleaphProcessEvent is not in the same thread as receiver, generate warning instead of critical message, and ignore event instead of aborting the whole register process
* change method signaure EleaphProtoRPC::registerRPCMethod back(return void instead of bool!)
Improve before and after PacketProcessed events by implementing some static EventResult handlings