* Added schema #2, two identical trees based on schema 1.
* Added and debugged test_delroot.test_root_target().
* Added and debugged test_delroot.test_multiple_targets().
* Found and fixed a bug in diff_trees() that was ignoring keys only in right_tree.
* After fixing issue in diff_trees(), now able to properly reproduce issue #18 in delroot/prune_dirs where specified target is not properly being deleted.
* Added test_use_root() to test_delroot.
* Added test_root_prefix() to test_delroot.
* Added test_dry_run() to test_delroot.
* Removed some commented code.
* Changing 'delroot' to 'rm'.
* Renaming test_delroot.py to test_rm.py.
* Converted check_output() to use universal newlines.
* Fixed issue #51: rm (formerly delroot) not properly handling invalid target.
* Updated info/warning messages in prune_files()/prune_dirs() to vary with subcommand.
* Added some additional debug messages to prune_dirs() and del_targets().
* Fixed issue #18: del_roots/prune_dirs not deleting root.
* Fixed --dry-run with rm and completed issue #44.