Performance improvements

[prydin]

After running my code in JProfiler, I found that a lot of time was spent in the numeric array reading methods. It turns out that length() and getValue() on the array tag were called tens of millions of times. Optimizing this part of the code cut the time to load a 1000x1000 map by 2-4 seconds.

[coveralls]

Coverage increased (+0.03%) to 89.352% when pulling e6cb656 on prydin:prydin-heightmap into c66dd6d on Querz:master.