Make login success reload carts

(Sadly, this is untested, as I can't log in right now)
Implement initial print job limiting and expansion button

As of yet untested, since I can't log into the test backend.
Fix print job length limiting and expansion button
Prevent people from directly printing empty carts
Properly escape URLs

I assume there will be quite a few carts with the name '//'.
It'd be a shame to error out on those.
Revert "Implement drag-based document multi selection"

This reverts commit 8cd92a5a8ead6cd1cb44cc395676c13293873f0d.

As drag'n'drop seems to be in a pretty sorry state in chrome/chromium
(pretty much no matter how you try to implement it), enabling this
feature completely breaks (non-add-all) document selection for chrome
users.

We'll have to think of something else.
(This does not revert Clippy. Clippy can stay (although disabled) until
we can think of a better way to explain how selection works to users)
Don't URL encode the same value twice.
Merge branch 'master' into release