Release: 0.7.19:
* added a new SubnetSplitter class for those looking to divide up subnets.
Thanks alanwill and RyPeck and those on (Stack Overflow discussion).
* removed bundled pytest dependency code for "python setup.py test".
* setup.py now uses setuptools only (no more distutils) and setup_egg.py removed.
* cleaned up INSTALL docs so they accurately reflect current Python packaging.
* fixed broken parsing, generating and reading of IEEE index files when switching
between Python 2.x and 3.x.
