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
I honestly have no idea if we should mention Mac OS X here. @kennethgillen: Does it seem to you that no Apple hardware makes sense for such a deployment?

Using versions with security support for "recommended" does make sense, thank you @rleigh-dundee for digging into the details.