EnumAction was erasing nargs before passing it to the superclass
initializer, which broke handling for arguments with consecutive values.
The help text for --desired-buyer has been updated to reflect that you
actually can specify multiple values with a single declaration now.
All scripts are now contained in a package named "bonemarketsolver".
The command-line interface has been moved to __main__.py.
The solver script has been moved to solve.py.
Relative module imports are now used where appropriate.
The invocation method of the CLI has changed: instead of running Python
itself, you can now use "pipenv run bone_market_solver".
The README has been updated to reflect the new usage method.
