[doc] minor clarification of how tags work.
[doc] Remove sphinx-extensions submodule.  Use 'PYTHONPATH=.../opendylan/documentation/sphinx-extensions make html' instead.
{test,suite}-definer now create constants bound to <test>s or <suite>s, not functions.
Merge pull request #44 from cgay/dev

Generate compiler warnings when tests or suites are unused.