Docs pruning (#5628)

* remove unused readthedocs template

* Doxygen API Docs, header and footer, remove depreciated config

* remove old vis

* remove homepage windowing js

* remove feed2js

* remove progtest docs

* remove isishistory and 'documents' structure

* remove old vis (part 2)

* remove unused toc and more unused javascripts

* remove one more utility js reference

* moved one-line files to inline in other files

* menu arrow fix for api docs

* move moon surface banner to be with rest of images

* reorganized images

* use menupath variable in more places

* remove unused blackborderimage css

* js.map files

* favicon

* css category fix

* css category fix part 2

* css category fix part 3