Clean up and optimize Breeds object.
Optimize Patch.leave
Optimize breed related functions

Breeds now keep track of their own turtles. This means looking up all members of a breed is now constant time.
Clean up updated

This is debatably faster. Try out this comparison of switch vs if-else: http://jsperf.com/switch-if-else/62. < 6 elements or so, if-else appears to be faster. Here, they’re tied for me on chrome, and switch definitely faster on ff.
Optimize fd by removing calls to canMove
Optimize jump by removing unnecessary functino calls
Merge pull request #58 from NetLogo/optimize

A bunch of optimizations