Added logic for factions that have access to major settlement tier 2 walls to build those walls at tier 2. Minors will still focus walls at tier 3, as they need slots for growth and income, etc.

Thanks to Incata for offering to let me use his tables zeroing out the "defense" spending category and lumping that money into military spending for the purposes of walls. That is an important part of his mod AI Military Construction System and I am hoping this will help get those walls up reliably in the midst of all the other stuff going on here too.

Added logic to prevent Wurrzag from duplicating barracks between the savage orc chain and the regular chain in a province.

Set a faction limit of 0 for Bretonnian barracks. I'm sick of seeing them built at all. They were getting stables, too, but now they will have a slot free for more economy etc.