Simplify conditionals and loops
Move constant to module level
Simplify another conditional
Add docstrings to all functions and classes
Add functions for version parsing/formatting
Attach the expected Emacs version to the exception
Check supported Python version
Merge branch 'refactor-bin-cask'
Add --version option that prints Cask's version.
Merge branch 'cask-version'
Fix version format docs.
Use commanders new auto docs feature.

Instead of describing the commands/options in the commander DSL, add
function doc-strings, which will be used as descriptions.