Improve quarry performance, updated build.xml. Correctly this time. 

Reduce getBlockId calls in canChangeBlock/isSoftBlock to one (world.isAirBlock also called it), add canChangeBlock/isSoftBlock with blockID parameter to allow for only a single getBlockId call per block checked for the visit list.
Use boolean[x * z] instead of boolean[][] for blockedColumns, java multidimensional arrays are arrays of arrays, using a single large array is better in most cases.

Signed-off-by: Ross Allan <rallanpcl@gmail.com>