Updated E3D Chimera Hot End OpenSCAD model

The Excellent OpenSCAD model of the Chimera by Professional3D, http://www.thingiverse.com/thing:1018787 needed some minor updates for the E3D 2016 version with heat break retaining screw holes on the side and the new sensor cartridge heater blocks.

Quick Points:

* The new blocks in particular mean you can mount left and right blocks and the blocks don't need to be in that strange 180 degree orientation, which will help with some mount designs.
The new blocks are ~3mm longer than before