Be more correct about this.  "::" indicates a class/module method.
This ensures better formatting behavior when generating docs.
Switching things over to RDoc.

Tried TomDoc but it was just an awful mess.  No syntax highlighting, no
support for producing a coherent documentation set, parser choked and
failed to document many methods, etc.
Converting RubyPants docs to Markdown so they'll be formatting nicely by RDoc.

... don't know if there's a way to get RDoc to treat one file differently wrt format, so just doing a quick conversion here.
Adding explicit issue links, handy for generated docs.