Escape hrefs

The link titles must escape the `:` character because the link definition uses the `:` character to separate the title and the actual link.  If you don't this you'll get rendering errors whenever the link title has the `:` character.

First cleaned up the test module with some minor pep8 fixes.

Also change is: https://github.com/jamesls/bcdoc/commit/7d54d5381f4812859a59eb45052c0c839acc112f