This version should be better:

* There should be no lines longer than 80 characters

* Changed coding style of the (private) XML plist writer classes
  to PEP8

* Public API is now dump/dumps and load/loads, the old API is still
  available and deprecated

  -> As mentioned before I'm not entirely sure if doing this is the
     right solution, but it does give us a clean path to remove
     deprecated functionality later on (in particular the Dict and Data
     classes). 
  -> What I haven't done yet, and probably should, is to write a 2to3
     fixer that converts code to the new API.

* Grouped source in more logical segments (deprecated, xml support, 
  binary support, generic code).

* The previous item means that I've moved even more code around, I looked
  into minimizing the patch but the original module could not be 
  easily extended without moving code around.

* Added some more tests
  -> I might add more tests when I manage to run coverage.py, for some
     reason the instructions in the dev-guide don't work for me with
     a framework install :-(

I might add a documentation comment to the binary plist support code that
gives an overview of the file format with pointers to more information, but other than that and possible test coverage improvements the patch should be done.