Many small improvements

Tuesday 10/20: Reworked the AI instruction system. Now each player has their own instruction queue. That allows me to add in a "freeze" instruction on the fly after marking to make the player wait a second before getting into defensive position. Also reworked (again) the way the AI chooses throwing targets. Now it basically will throw it to anyone that's open.

Wednesday 10/21: Added texture mipmapping (makes the field look better in the distance). Angled the stack based on the disc position. Added a "turnover"when the disc hits the ground. AI will stop throwing motion if the target becomes no longer open.