working LoaderGCode example;

A working example for LoaderGCode, which displays the toolpaths of a GCode file in 3D.  Corresponds to the pull request at https://github.com/MasDennis/Rajawali/pull/1061.

The example works but the orientation is not proper.  The cube is upside-down!  I've had a tough time getting the camera position proper - and rotation just doesn't work the way I want.  Maybe you know how to fix this or am I doing something wrong in the parser or renderer?