VMM/Transport: reworked Transport class. Use assertions for argument checks. Removed methods getID() and getTransport(). This values are now accessible through the read-only attributes id and transport. VMM/{Account,Domain}: adjusted to modifications in Transport class. A few code cleanups.

# -*- coding: UTF-8 -*-
# Copyright (c) 2007 - 2010, Pascal Volk
# See COPYING for distribution information.

MISSING_ARGS = 1
UNKNOWN_COMMAND = 2
USER_INTERRUPT = 3