Provide a toolkit-agnostic interface for "busy indicators", which
allows the 3D viewer to show a busy cursor, without the canvases
having to to know how a wxCursore works.
The motivation here is to decouple the 3D renderers from the WX
GUI system, as they can then be used when when there is not an
active window (e.g. for offscreen rendering).
Otherwise, attempting to use a wxBusyCursor without a GUI
available is an instant segfault.
* Split and rewrite the preview window and canvas.
* Create a new class for handling the board information.
* Adds new render targets: openGL, legacy, and ray tracing.
* Render targets take full advantage of the new 3D plugins system and 3D cache
for a fast 3D model loading.
* Faster board loading.
* New OpenGL render is faster than the old one.
* New ray tracing render target with a post processing shader.
* Use of new 3D plugins (WRL, X3D, STEP and IGES) and 3D model caching.
* Preview of 3D model while browsing the file name.
* 3D preview of the footprint while adding / align 3D shapes.
* Render of 3D models according to attributes: Normal, Normal+Insert, Virtual.
* Pivot rotation centered in one point over the PCB board.
* Shortcuts keys improved for XYZ orientation..
* Animated camera.