Update deepreload to use a rewritten knee.py. Fixes dreload(numpy). knee.py, a Python re-implementation of hierarchical module import was removed from the standard library because it no longer functioned properly. deepreload.py is little more than a hacked version of knee.py which overrides __builtin__.__import__ to ensure that each module is re-imported once (before just referring to sys.modules as usual). In addition, `os.path` was added to the default excluded modules, since somehow it has an entry in sys.modules without `os' being a package.