Add working set of Sphinx extensions.

Refs #9521
Add README and initial start on style guide text.

Refs #9521
Update screenshot method to add CSS class to image. Refs #9521.

- This is required to easily style the image, e.g. alignment.
Removed title from categories. Refs #9521.
Added local table of content to algorithm. Refs #9521.
Use figure rather than image. Refs #9521.

- This allows a caption to be added that contains the algorithms name, to make the screenshot's purpose clearer.
Hard code section header names rather than using the module titles

It's clearer where the section names come from and avoids any unwanted
module qualifications when the directives become part of a package.
Refs #9521
Add supporting code to generate screenshot in algorithm directive

Refs #9521
Add gitignore & README for images directory.

Refs #9521
Add initial config file. Refs #9521.
Add custom styles to sphinx-bootstrap theme. Refs #9521.
Create empty globaltoc template to remove button in nav. Refs #9521.
Moved static and template folder to source. Refs #9521.
Add in html logo and tweak css

Refs #9521
Require versioned algorithm files

Implements a test for a simple redirect system to the highest version
Refs #9521
Protect screenshot capture if the GUI is not present.

Refs #9521
Forget to add category & redirect templates

Refs #9521
Track highest versions of algorithms encountered

Redirect pages are created that point from a page using the plain name to the highest version page
Refs #9521
Purge category information before parsing document.

Refs #9521
Only insert alias section if one exists.

Refs #9521