improve and update server configuration documentation (rebased from develop)

Makes a start on the work for https://trello.com/c/Gpwp1WkC/188-improve-server-config-docs and removes some information about both OMEIS archeology and, from https://trello.com/c/avvIvqCk/67-5-0-3-follow-up, our long-neglected OpenGL clients.
--rebased-from #948
Sorry, I didn't notice the bit about it being a rebase, in which case most of my comments are probably best left for a separate develop-only PR, unless you wanted to bump the recommended versions here.