The Client should be able to go Space-to-Space without reloading

(Incomplete Feature, Investigate , Priority: High, Test Status: No automated tests yet , Reported By Justin du Coeur, )
Internals, User Interface
Summary: Currently, whenever I go from a Space to index, and thence to another Space, it reloads the entire Client twice. This is annoying and slow; we should be able to cope with switching within a single Client.
This is not a small change -- it affects how we load the Client and Space in the first place, and will touch a lot of code. But it will improve the overall experience markedly.
This may want to be folded in with the changes to make the Client capable of understanding multiple Spaces at once.