Added support for 2D shadow casters.
*DANGER* Shaders in CanvasItem CHANGED, if you are using shader in a
CanvasItem and pull this, you will lose them. Shaders now work through a
2D material system similar to 3D. If you don't want to lose the 2D
shader code, save the shader as a .shd, then create a material in
CanvasItem and re-assign the shader.
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-Auto indenter in code editor, this makes it much easier to paste external code.
-Zoom in 2D viewport now uses the mouse pointer as reference.
-Obscure hack to see where code/line of GDScript in C++ backtrace.
-Fixed a bug where keys would get stuck on X11 if pressed simultaneously
-Added Api on IP singleton to request local IPs.
-Premultiplied alpha support when importing texture, editing PNGs and as a blend mode.
