1: em_utils_reply_to_message() can be passed a newly-created message (from
a current selection. It needs to unref it. Which means that when we pass it
a message which *isn't* newly-created, we have to obtain a ref of our own.
It was that or add a boolean parameter to tell it whether to unref or not.
2: emf_finalize() wasn't unreferencing emf->message -- so when we clone
the EMFormat in em_utils_message_to_html() and immediately unreference the
clone, a refcount on the message got leaked. Fix emf_finalize() to unref
emf->message as presumably it should.
8ae4bf802a