More python 3.x fixes.
More python 3.x fixes: keep __hash__ and __eq/neq__ redefinitions together.
More python 3.x fixes:

  * Suppress 2to3's "next" fixer that conflicts with having non-iterator attributes called "next."
     Rely on six.next instead.

   * added python 3 version of hash_from_code.
More python 3.x fixes:

  * Use PyCapsule instead of PyCObject.

  * Use Python 3 module initialization.

  * Prepend 'm' to code hash to avoid module names that start with a digit.