runtimetest: Make TAP output more granular

Granular TAP output makes it easier to see what's being tested (and
what's going wrong).  You'll want a TAP harness looking for test
failures, because runtimetest now returns a lot of information, most
of which is (hopefully ;) about passing tests.  In order to accomplish
this change, I've setup a complianceTester structure to make it easy
to pass the TAP harness down into the helper functions.
complianceTester also holds the target compliance level, so it can
decide whether a spec violation is sufficiently serious to be a failed
test violoation or is minor enough to be a warning.  I've used skips
for the warnings, since they seemed like the closest fit from the TAP
spec.

And I've made a number of other improvements while I was working
through this, but haven't written them all up in this commit message.

Signed-off-by: W. Trevor King <wking@tremily.us>

Author: wking