Reimplement ztext parser to not take substrings everywhere

Seems to be faster. Consistently faster in Firefox and faster in V8 after a
couple iterations.
Append nodes directly to the parent

Doesn't seem to help a whole lot, but I guess this is probably better than
appending fragments to each other? Firefox just seems to not be super-fast at
creating nodes.
Actually check for missing user in stub auth code
Add code to create users which don't exist
Still clean up if cancel subs fails
Set up an empty ccache on startup

Otherwise ZGetSender caches the wrong value and gets confused.
Handle crashed inner demons

Pending commands should fail.
Use ZSubscribeToSansDefaults

We don't want the defaults. Especially not in the inner demons.