fix exports in Internal
add type delcaration to runHandlers and don't pass write sem to startThreadsWith
move from exceptions as StreamHandle error indicator to XmppFailure error values.

This changes the return type of at least the following functions from IO Bool to IO (Either XmppFailure ())
  * sendIQ

  * sendIQ'

  * answerIQ

  * sendMessage

  * sendPresence