Use except as for Py3k compatibility.
Alias str to unicode for Py3k compatibility.
Use print_function from __future__ for Py3k compatibility.
Enable Python 3.4 support.
Use codecs.decode instead of str.decode for Py3k compatibility.
Use range instead of xrange for Py3k compatibility.
Drop support for python-dateutil 1.x due to Py3k incompatibility.
Document all supported Python and python-dateutil versions.