Functionality to gather statistics of completion

[mloyanich]

I have added the functionality to gather statistics on the completion of the problems. The statistics show Total, Done, and In Progress for all the problems and broken down by the level of difficulty.

The new key for stats is -b. The output looks like this:

I have added colors for easier readability

[mloyanich]

oh, just realized that the first number is not total. let me add one more commit here