ReproNim sphinx theme/template

[yarikoptic]

for a more consistent appearance of existing (e.g. https://heudiconv.readthedocs.io) and upcoming (for the rest of the project) project landing pages (where sphinx would be used)

[satra]

depending on the project you can switch between sphinx and mkdocs. readthedocs suports both.

[satra]

also heudiconv needs to have the google analytics code inserted. i don't have access to it for repronim. perhaps someone can add me in on the google analytics portal.