Add unix group functionality back into utils.path
utils.path: allow the pattern argument for various methods to take a compiled regular expression pattern.
utils.path: add path comparision methods: samepath, canonicalpath, and truepath.
util.path.walk and walkdirs: patterns should filter directories, and also prune all of their children.
util.path: add realpath argument to file/directory listing methods: listdir, dirs, files, walk, walkdirs, walkfiles
util.path: check for infinite recursion due to symlinks in walkdirs()
util.path: improvement to earlier chgrp and get_groupname commit.
util.path: provide regex argument to walk, walkdirs, and walkfiles, which allows for passing an uncompiled regex string.  the pattern argument is prefered over this one.
Merge branch 'path_edits'