Add CLI interface

[hollop90]

Adding a versitile CLI interface would make running the solutions much more confortable.

The features that this CLI should include are (but not limited to):

• Printing statistics
• Running all or any combination of days
• Timing each day and the whole challenge too

[hollop90]

maybe a profiling option would be nice too. run every day (or a particular day) many times to get run time statistics