* All items shapes are converted to polygons.
* Polygons are merged layer by layer (for calculation time reasons,zones are not merged)
* for copper layers, vias and pads holes are substracted from polygons (but, for calculation time reasons, not inside zones areas).
* the look is better, mainly when displaying the copper thickness
* solder and paste layers are now shown in 3D viewer.
* the code was seriously cleaned (but still needs to be enhanced).
* Note this is a work in progress which needs refinements.
jean-pierre charras