The library should now generate the proper stream errors again, in
case of received stream open element problem.
The return type of streamS has been modified so that the validation
can be performed in startStream instead, and without exceptions. This
will also help enable implementation of logging later.
The Errors module has been removed.
StreamError has been renamed to StreamFailure, as it's neither an
error or an exception, and since the term "stream error" is ambigous
(it can also refer to the stream error element on the XMPP stream).
Furthermore, XmppTLSError has been renamed to TLSFailure.
The data types related to the above mentioned failures are now
exported.
We do no longer clutter the API with detailed error conditions such as
StreamNotStreamElement. These kinds of conditions are such rare
occurances, and details about them are better suited in the logging
system (to be implemented soon).
Stream failures can occur either when a `stream:error' first-level
XML element is encountered, or if something unexpected happens in the
stream. Currently, `StreamErrorFailure', `StreamEndFailure', and
`StreamOtherFailure' are defined for these purposes, but additional
exceptions can be added if that would be helpful for the developers.
TLSFailure is moved to Types.hs and is now exported.
Also temporarily removed findStreamErrors.