mirroring/Tortoise: don't cache AgentKeys

this is a prospective fix for NetLogo/Tortoise#1

even assuming this change turns out to do the trick (we won't know
until after a string of successful Travis runs), note that it does
substantially increase memory usage for recording model runs. after
all, reducing memory usage is the reason we added the caching in the
first place.  so we may end up confronting this again.
latest models
Add tests round 1!
Change tests to fail correctly
In progress: Add basic breed statement
Add breeds phase 1: is-breed? and create-breed

Had to also add in some extras like world.getTurtle(id) and whatnot
Add case for orderedturtles!
In Progress: Breeds
Add set-default-shape.

This also has a complete reworking of the underlying breed
representation threaded through it.  I couldn't extricate it into a
separate commit.
Add hatch.

It has a breed too!
Add <breed>-here.
Add <breed>-here part 2
Add Sheep Wolf!

Of course it deviates when you go more than one step!
Make turtle.toString use breed name!
Merge branch 'tortoise-breeds' of github.com:NetLogo/NetLogo into tortoise-breeds