Moved walk() and print_tree() to mcdata.nbt and updated examples.
Removed obsolete regiontest.py.
print_tree() now hex encodes bytearrays.
Added __enter__() and __exit__() to RegionFile. (Can now be used with "with".)
Rewrote print_tree() and improved output format.
Bugfix: lists were walked in the wrong direction.
Added NOTES.