[c1992] AI-Event throwing and receiving implementation
[c1993] Add ACTION_T_THROW_AI_EVENT and EVENT_T_RECEIVE_AI_EVENT to EventAI

Also introduce new target-type TARGET_T_EVENT_SENDER (only valid with EVENT_T_RECEIVE_AI_EVENT) to know who sent a received event

Note: This system is still in development, but this should already give many nice powers for first improvements and uses
[c1994] Add support for client 1.12.3 (build 6141) to realmd
[c1995] Fix a VC90 compile problem. Also add some const correctness