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

Reduce getBlockId calls in canChangeBlock/isSoftBlock to one, add canChangeBlock/isSoftBlock with blockID parameter to allow for only a single getBlockId call per block checked for the visit list.
Reduce chunk hashmap lookups to the number of chunks in the quarry area.
Use chunk heightmap when building visit list

Signed-off-by: Ross Allan <rallanpcl@gmail.com>