README.txt and README.md

[micahcochran]

Having both of these files causes confusion. They are not kept in sync with one another. For the most part the text version seems to have had some more extensive edits.

The Markdown version can be improved using guidance from the CommonMark spec to be made more readable from a text editor. Also, Markdown can be converted to many formats using pandoc or similar converter.

The doctest seems to work fine with the markdown version, but it does find about 25 fewer tests.

It seems like they were basically the same file on March 11, 2014.

I propose removing README.txt, retargeting the doctest to use README.md, and include changes made to README.txt for inclusion to README.md.

The only issue I can see is that README.txt has release version, author, and release date. This could be maintained in a separate file such as perhaps a RELEASE.txt file.

[micahcochran]

Resolved by issue #61 being merged.