Exception hardening

[ohlidalp]

This should put a stop to the game panicking on any unhandled exceptions, which are usually trivially recoverable, like this dialog which was caused by a .mesh file missing from a terrain:

All exceptions which happen during processing message queue are now automatically logged to RoR.log and also forwarded to AngelScript as game event - a trick already widely used in OGRE bindings, see SE_GENERIC_EXCEPTION_CAUGHT.