Message bases, express messages, and navigation good enough to use

At this point, while there are still some glitches being worked out, things are working in navigation, message base entry and reading, and the like well enough for this to be used for a reader. There are a lot of things still missing, but this implements minimum usable functionality. I think this is a good candidate for alpha release, so that I can finally get those tags in sync and give us a little more concrete milestone showing a shiny for all the work that we've done.

Around this stage we've also got some other developers stepping in to help, and probably some testers coming soon. Beta will be released when Mail> and a couple of other key features (ie menu pagination and the like) are working as well. We're damn near there.