Version 1.3.1 of vu.

Refactor and simplify. Change highlights are:
  o vu/move: Focus physics on box and sphere shapes. Add a physics
    solver based on bullet physics btSequentialImpulseConstraintSolver.
  o vu/device: Replace SetFrontProcess for Osx 10.9 compatibility.
    Update to golang 1.2 which removes the Osx dylib dependency.
  o vu/math/lin: Have all math and physics use float64.
    Combine location, rotation in a separate transform class.
  o vu/render/gl/gen: Simplify the binding generator.