garbage collection tests on quick state changes

- both increase in memory very quickly , garbage collector is slow but ultimately gets to each of them (pooling system seems to clear up fine.)
- with 50 bodies, box2D has apparently needs a lot more objects to make them run, resulting in a very big increase as state changes - and so slower gc... nape apparently needs (I'd say exponentially) less memory ...
Or there is something wrong with how crates are destroyed in these examples.