add BNW support and a better hero system

remove blizzard assets and make it based on historical settings now.

Fix a bug that flying units embark into water after druidism
Fix a bug that Sensors built by Terran Raven make game stuck
Fix a bug that militaristic citystates send settlers
Fix a bug that workers can't build improvements automaticly
Add a button at ability panel to locate the nearest revealed barbarian camp
Combat strength for Cities start lower and grow faster
AI heroes now have higher level, HP, use skills more clever and perform better in general
Stronger units for Barbarians available at earlier time

Fix a bug that Treasure Hunt make Hero not able to move for ever
Fix a bug that you can't kill enemy units with more than 100 damage with melee attack
Fix a bug that game crash when a Hero upgrade to Gantrithor or some other super units
Fix a bug that you can't conquer AI capital
Reduce mana bonus on some prefixes
Grant AI player bonus free buildings, you can setup the game 1 or 2 level lower on difficulty, and Deity is really hard now