Add documentation for unused contexts test.
Add test for namespace.parse_xmlns function.
Add tests for namespace.fixup_element_prefixes.
Add tests for xmlns writing.
Update TODO.md.
Dynamically retrieve version and remove esky.

Add _version.py to hold the project version number and make setup.py and
thinX.pyw dynamically retrieve from it. Also remove remaining esky
references from thinX.pyw.
Make the xbrl.dup_calcs function handle subsets.

Modify the xbrl.dup_calcs function so that it reports subsets of
calculations. Also update the unit test to expect subset calculations.
Version bump to 0.7.0.