WIP Search docs and sdk to find undocumented libs

Usage:

~/gits/addon-sdk $ python \
python-lib/cuddlefish/docs/completeness.py lib/sdk/ \
doc/module-source/sdk | less

This outputs some reports:

* Modules that have documentation
* Documentation with no libraries
* exported things that have no <api> tags
* <api> things that have no associated code.

TODO:

* check that reporting is accurate.
* use better methods than my regexes
* generalize for package paths?
* decide on format of report?  HTML?
* decide if <api> should have a 'nocode=true' to allow ignore?