AI spell casting priorities

[ologm]

Having played MA ulm in single player recently, I can confirm that flying shards gets cast too much.

Summon earth power has too low a priority as my smiths would almost never cast it without scripting. While it is quite useful.

Another thing is that the smiths really prefer casting legions of steel and weapons of sharpness on my independent archers instead of my heavy infantry marching toward the enemy.