Make argument and option section IDs more unique

[djhoese]

Closes #43

This adds the module name and function name (attribute name from the module) to the beginning of the section ID for Named Arguments and options sections. This allows the IDs to be unique and for sphinx to keep section numbering consistent. See the referenced issue for more information.

I'm not really sure how to add a test for this. Also this does not effect subcommand section IDs as I'm not sure I understand how those are structured. This PR solves my immediate problem.