Complete rewrite of bottleneck!

Requires numpy 1.8

A few enhancements and bug fixes

Bottleneck 0.6.0

First release candidate of Bottleneck 0.6

Four new functions, single source dist, bug fixes.

rankdata and nanrankdata crashed on win64

argpartsort, nanargmin, nanargmax returned wrong dtype on win64.

32/64 bit clean up.

Second beta of Bottleneck 0.5.0.