ADDED: Checks for SendChatMessage() function's types and languages

* Chat.cpp/Chat.h: New function and prototype: CheckChatMessageTypes()
** This function can handle player and creature chat messages.
** Returns false on occurence of wrong types and uses error log function.
* Creature.cpp/Player.cpp/Unit.cpp/UnitFunctions.h: Implemented
  CheckChatMessageTypes()
** SendChatMessage() functions will abort if CheckChatMessageTypes()
   returns false.