Remove or update 'fixedpickle' module and dependency

[robclewley]

A 2006-era python built-in 'pickle' serializer module was patched to allow pickling of IEE754 special values NaN and Inf on Win32 when cpickle was not available (original could not load these correctly on Win32 platforms).

http://bytes.com/topic/python/answers/501305-numerics-nans-ieee-754-c99

Not sure what the status of this issue is now, but it doesn't seem to have been fixed. However, the provided module is out of date and can crash on some platforms. It should either be extracted and all 'fixedpickle' use should revert to default 'pickle', or load_float method's patch (approx line 981) applied to a recent version of 'pickle'.