An improved cmd.py for Writing Multi-command Scripts and Shells
`cmdln.py` is an extension of Python's default `cmd.py` module that provides "a simple framework for writing line-oriented command interpreters". The idea (with both cmd.py and cmdln.py) is to be able to quickly build multi-sub-command tools (think cvs or svn) and/or simple interactive shells (think gdb or pdb). Cmdln's extensions make it more natural to write sub-commands, integrate optparse for simple option processing, and make having good command documentation easier. Python 3 compatible module.