Docs tweaks

- make clean now also removed the autogen'd modules dir
- image moved to static content dir, link updated
- man page builder is now the dev_guide (though having one man page of all the docs was hilarious, and I know nobody uses this anyway...)
- tweaked the html title to leave out the version
- 'tries' argument of force_navigate is now obviously private
Merge pull request #407 from seandst/docs-tweaks

Docs tweaks