Cleanup cython imports and remove no longer needed workarounds

Ignore-this: 10203982ed6d67cbde5208fb67258aa2

darcs-hash:20130917144754-56b4d-214a576ec52a9c45033db73fac0a4498e69ff987
Linking with frameworks only applies on OSX

Ignore-this: 2288187900034f066cbedf7dc0e1261d

darcs-hash:20130917145552-56b4d-0d5551ebef50b2e5ea29ef5859d299c66cea4013
Keep things organized in categories

Ignore-this: 5bad105c60ec72546856295894ca4bd1

darcs-hash:20130917173126-b22ec-6b6f954b3332a3a335370dbb10f98638a9c7e771