Merge new setup wizard
This is much more up-to-date than the previous setup page, with a new
design and previously missing/new settings. Currently only available in
english (hopefully that changes soon).
also fixes conflict in _post.
Also make store each setting as classes in a settings object, to make it
easier to serialize on submitting. Also, added
"substitute_jellyfin_strings", "no_username" and welcome_email.
the web ui has been redesigned with the a17t toolkit, which imo looks a
lot better than bootstrap. This also brought a complete rework of the
web code, which now makes a lot more sense hopefully. the setup page is
still stuck with bootstrap, its not much of a priority but i'll rewrite
it eventually.
parseDT only uses the magic json.Unmarshal method if theres an error
with the better version. Error came from some times being sent without a
"Z" at the end denoting UTC.
web UI now uses modules, and relies less on bodge to make things work.
Also fixes an issue where invites where "failed to send to xx" appeared
in invite form.