small fixes + update

Originally, this fixes a small merge glitch that prevents OS X from building.
But in the end, I worked a lot more:

- update the Python and C files to include all 2.6.8 and 2.7.5 changes
- update the Python and C files to include all 3.2.5 and 3.3.2 changes
- rework the 2.X tests to be a complete merge of pickle and cPickle tests
- update the DOAP record to 0.5.1 and mention OS X
- added fastpickle and slowpickle modules to give the user a simpler choice

I successfully ran all tests on OS X.
Hope this request is acceptable and useful.

Cheers - Chris