fix Prims.sort to be nondestructive
add `reverse` prim (for both lists and strings)

tests for this already exist in the language tests.  it's also used in
some tests whose main purpose is to test other things, so it's good to
have.
fix bug where `sort` mutated input agentset
minor cleanup
Merge pull request #81 from NetLogo/make-sort-nondestructive

fix bug where `sort` mutated its input list
Reorging tests
Making agentsets of patches sortable
Fixing some list-sorting language tests
the real Vants works now

(removed the old Tortoise-only version from the models repo)
make TestModels support overriding dimensions

the old method of using `resize-world` to override was
unsatisfactory because the full-size world would get created
before we had a chance to override it, which could be very slow
for very large worlds (e.g. CA1D Benchmark)
add support for _clearturtles and _clearpatches
use webjars-locator

and eliminate webjars.sbt for now. some form of it might come back
later as part of support for V8-based testing and/or browser-based
testing

for gory details, see discussion on HipChat today
CA1D Benchmark crosses the finish line
Merge pull request #84 from NetLogo/sortable-lists

Sortable lists
State Machine Example crosses finish line

plus get newer version of Sandpile from models repo that
uses fewer workarounds (since tasks work now)
update model dumps
speed up TestModels by diminishing problem sizes

smaller worlds, shorter runs
Merge pull request #83 from NetLogo/webjars-locator

replace webjars.sbt with webjars-locator
Getting a `resize-world` language test passing
Recategorizing failing language test