Call TLS.getBytes again on EAGAIN

Since that's what the manpage says to do, and without it we sometimes
end up crashing when calling again would have worked.

Purge OverloadedStrings

hlint clean

Fix some whitespace

Don't need typable for exceptions anymore

Add Internal module

A message with no "type" is of type "normal"

Workaround for stream-xmlns issue

From my notes:

I discovered that it expects "{jabber:component:accept}jid" instead of
"{jabber:component:accept}id" for the stream id, which is against the spec.
Additionally, if the server sets the default xmlns to jabber:component:accept
it seems that the id attribute is parsed as having no xmlns and so does not
get found.

Remove call to TLS.setPriorities, because the underlying libgnutls
function has been removed in recent upstream releases.

TLS connections seem to work fine without this call (tested with
talk.google.com), so I don't know if it was ever even needed.

Bump version to 0.4.8.

XMPP's open-coded ErrorT needs Applicative

If auth fails, include the error element in AuthenticationFailure.

Add 'sessionIsSecure' function, so users can check whether the current
session is running over a secure channel.

Support authentication schemes that require post-success validation.

Fixes authentication failures with the SCRAM-SHA1 mechanism, reported
by Gergely Risko.

Clean up Cabal file.

Bump package version to 0.4.1.