Add more detailed module-level documentation for all algorithms.

[afck]

Every module should have an extensive description of what it does, and maybe even a short explanation of how it does it. (That explanation would be needed in the code anyway, to make it readable at all, so why not make it part of the module docs themselves.)

Once the API is stable (#66), we should add a usage example to every module, too.

[afck]

honey_badger is still missing docs. (And so is queueing_honey_badger, once it's merged.)