Useful for everybody wanting to package godot.
Fixes#1026.
-> Retain the old behaviour: path in error msg only when exporting.
-> User templates override system templates
-Visible 2D and 3D Shapes, Polygons, Tile collisions, etc.
-Visible Navmesh and Navpoly
-Visible collision contacts for 2D and 3D as a red point
-Customizable colors in project settings
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-Sprite3D and AnimatedSprite3D support.
-Opaque pre-pass works, is compatible with shadows
-Improved shadow map rendering (can differentiate between plain opaque and opaque with shaders/discard/etc)
-Added option to use alpha discard in FixedMaterial
-Improved Glow FX, many more options (three modes, Additive, Screen and SoftLight), strength and scale
-Ability for Background (image or cubemap) to send to glow buffer
-Dumb Deploy of clients now actually works in Android
-Many Many rendering fixes, 3D is much more usable now.
