CLY is a Python module for simplifying the creation of interactive shells. Kind
of like the builtin `cmd` module on steroids.

It has the following features:

  - An XML (honestly, it's better than you think) grammar format.

  - Tab completion of all commands.

  - Contextual help.

  - Extensible grammar - you can define your own commands with full dynamic
    completion, contextual help, and so on.

  - Simple. Grammars are constructed from objects using a convenient
    ''function-like'' syntax.

  - Flexible command grouping and ordering.

  - Grammar parser, including completion and help enumeration, can be used
    independently of the readline-based shell. This allows CLY's parser to
    be used in other environments (think "web-based shell" ;))

  - Lots of other cool stuff.