Added edit, man, python. Added & to stash.py word_chars

I've added:
man.py - lists programs in /bin and displays thier docstring.
edit.py - opens a file in the pythonista editor
python.py - allows execution of .py files and monduels

added '&' to _word_chars in stash.py - I needed this to allow running a python script in it's own thread emulating bash &.