Major cleanup of many icons (started as a simple effort to tweak libedit and modedit icons)
Ref: https://lists.launchpad.net/kicad-developers/msg32860.html
* Each application icon has been updated
* Consolidated icon "modifiers" across many icons
* Replaced confusing arrows with "load" and "save" icons
* Slight code updates to reference correct icons
* Consolidate multiple representations of single icon type(s)
* 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.
Seth Hillbrand
Oliver
Baranovskiy Konstantin
Mrio Luzeiro