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.
