Cleanup/reorganize the simple_stats module

[brifordwylie]

The simple stats module is a bit of a mess and needs to have both the internals cleaned up and the outputs changed.

Suggested outputs:

• contingency table (raw counts)
• conditional distribution (row proportions)
• conditional distribution (column proportions)

[brifordwylie]

okay most of this has been done on the stats-work branch and merged into master. I'm going to leave this open and after some cleanup-testing I'll close it.

[sooshie]

Cleaned up a bit more and added some functionality back in (specifically N and matches)