Pre-commit hooks

• block_bad_path_names.py: reject all files/directories with whitespace & forbidden windows characters

• block_monitor_commit_tests.py: hook to test svn and hooks but block the commit before a revision is created (used for monitoring, run last in the chain)

• block_some_prop_mods.py: block properties with bad names or gvn:superusers node prop

• bypass.py: allow skipping all remaining hook gvn:bypass-hooks if committing user is in the superusers list

• check_changebranch.py: block users from mucking about with other users' changebranch areas