Extends doorstop issues and outputs to separate files.

The item_hook function passed in to doorstop's tree.get_issues() defines
new project specific issues to look for.

I recently added tracing between the SWR and SDD documents and I hadn't
been consistent when it came to tracing the buttons.

This looks for words commonly used only in button requirements and makes
sure the lower level requirements that should trace to the SWR button
requirements do.

It also checks the requirement text to make sure they all have 'shall'
in them. It found several that did not.