Fix visible HTML entities in chat messages (#36)

For lines of text that don't contain any link, but do contain a HTML
sensitive characters like ", those characters will still be replaced by
their entity values (e.g. &quot;). TextEdit.AutoText does not consider
those to indicate rich text, so they will be displayed verbatim.

Since we always escape HTML characters, we should always parse the
output as HTML, and entities will be correctly decoded.