More 3D Improvements

-=-=-=-=-=-=-=-=-=-=

-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.

servers/visual/shader_language.cpp

@@ -1034,7 +1034,7 @@ const ShaderLanguage::BuiltinsDef ShaderLanguage::fragment_builtins_defs[]={
 	{ "SPEC_EXP", TYPE_FLOAT},
 	{ "GLOW", TYPE_FLOAT},
 	{ "SHADE_PARAM", TYPE_FLOAT},
-	{ "DISCARD", TYPE_FLOAT},
+	{ "DISCARD", TYPE_BOOL},
 	{ "SCREEN_UV", TYPE_VEC2},
 	{ "POINT_COORD", TYPE_VEC2},
 	{ "INV_CAMERA_MATRIX", TYPE_MAT4},