Add command reference etc. to man page.
Use mandoc instead of groff for HTML manpages.
Add stylesheet option for mandoc.
Remove unnecessary square brackets in README urls.

Substituting [x] for [x][] *should* work.  If not, I'll revert this commit.
Tweak the Readme.

This removes the Q&A, rewords and shuffles various things, and makes the
'elevator pitch' at the front more straightforward.
Readme: Make FreeBSD a sub-header under POSIX.
Add more documentation to io_core classes.
Add some comments to io_response.
Merge pull request #58 from UniversityRadioYork/mw-documentation

Various documentation changes