WIP - Make plugin a port of sphinxcontrib-graphviz, since that plugin…

[stuaxo]

WIP - do not merge !

This is a (very) rough start at making sphinx-shoebot be a port of graphviz-shoebot.

sphinxcontrib-graphviz is a plugin by the sphinx org which uses code to render images, so is suitable to alter to render shoebot plots.

Advantages:

• support formats other than html (still to port)
• properly outputs images to the build directory (lack of images on readthedocs was a side effect).

Currently this just proves the concept works.

Sample: https://shoebot.readthedocs.io/en/feature-readthedocs-temporary-fix/

html output:

• Fix CSS (structure has changed so styling needs updating)

latex output: TODO

pdf output: TODO

man page output

• Initial version implemented.

text outpit

• Initial version implemented