First draft of README alterations

* Rename README files to README.md and link from root.
* Rename HACKING to HACKING.md and link from root.
* Add additional links.
* A fair amount of added punctuation and rewording.
* Replace references to darcs/trac with git/github.
README: fix local links

* Attempt to fix local links.
* Experiment with syntax highlighting.
* Add title to HACKING.
* Reword an awkward sentence and a few wordy headings.
* Change "Unix" to "Unix-like".
README: Additional changes regarding links
README: rename tests/README and update .cabal files.

* Ensure README.md is in .cabal files.
* Remove some verbiage.
* Remove broken link to old wiki in HACKING.
README: Reformat tests/README

* Reformat tests/README, add links to individual files.
* Add link to tests/README to HACKING.
* Add links to license files.
README: Fix links

For some reason github is finicky when it comes to local links. Also,
I'm dyslexic it seems when it comes to Markdown's link syntax.
README: fix tests/README link and add one to detailed test runner source
Merge pull request #1776 from ianbollinger/update-readme

Update README files