Nuke many log lines

We were always logging effectively in debug mode, but with the amount of active
use we have this was both a possibly privacy issue and make uselessly big log
files.  I haven't looked at most of this in ages, so take it all out until
something calls for it.  Things mostly work these days.
First draft of grouptext porcelein

Works, but does not pass through anything yet if target supports it, and may be
otherwise a bit rough.
Import XMPP internals because we use them

This makes cheogram actually compile with newly released upstream instead of
needing a patched version.
Fixup cabalization
List all needed modules in cabal file
Remove chattiest low-value log
Only say could not join if tried to join
IQ replies should come from the full JID that requests went to
Pass through IQ errors when reasonable
Update to work on latest Debian stable
Strip OTR whitespace from whispers

This will break opportunistic (but not explicit) OTR support in any
backends, but none currently have such support.  It will also break such
OTR for and pass-through, but really we should do pass-through in
Cheogram itself eventually.

Benefit: not delivering weird whitespace over SMS, which currently all
known backends choke on anyway.

Closes #67
Advertise ad-hoc commands support
Workaround for ChatSecure bug

They send receipts to our "don't message me" message, even though we
didn't ask for one.
Pass through command list from direct route
Add missing space
Remove this until we get a consent system

Some people consider their JID to be private information.
Suppress welcome message for token sends
Improve new-user UX and copy
Do not ping MUC participants who are not ours

We can't rejoin them anyway