Simplifying and extending the LuaAI subsystem

by Nephro for Battle For Wesnoth

Right now, the LuaAI system is in a state, where it can be used for artificial intelligence system development for Battle for Wesnoth campaigns, but it's usage is quite complicated and requires effort to get the system off the ground and make it run. To simply to launch a campaign with an empty LuaAI(by empty, I mean, not doing anything) a UMC developer is required to write a couple dozens of lines of code(not even mentioning the bugs that he will encounter on the way). While it seems, that we could simply hide the boilerplate code in a template or behind a macro, the situation is a bit more sophisticated(Later I will describe that in more detail). Instead of running away from this problem, I will work towards an elegant solution, creating an effective back-end system, and a clean user development environment.