Renaming of servers for coherency.

VisualServer -> RenderingServer
PhysicsServer -> PhysicsServer3D
Physics2DServer -> PhysicsServer2D
NavigationServer -> NavigationServer3D
Navigation2DServer -> NavigationServer2D

Also renamed corresponding files.

servers/rendering/rasterizer_rd/shaders/canvas_occlusion.glsl

@@ -0,0 +1,40 @@
+/* clang-format off */
+[vertex]
+
+#version 450
+
+layout(location = 0) in highp vec3 vertex;
+/* clang-format on */
+
+layout(push_constant, binding = 0, std430) uniform Constants {
+
+	mat4 projection;
+	mat2x4 modelview;
+	vec2 direction;
+	vec2 pad;
+}
+constants;
+
+layout(location = 0) out highp float depth;
+
+void main() {
+
+	highp vec4 vtx = vec4(vertex, 1.0) * mat4(constants.modelview[0], constants.modelview[1], vec4(0.0, 0.0, 1.0, 0.0), vec4(0.0, 0.0, 0.0, 1.0));
+	depth = dot(constants.direction, vtx.xy);
+
+	gl_Position = constants.projection * vtx;
+}
+
+/* clang-format off */
+[fragment]
+
+#version 450
+
+layout(location = 0) in highp float depth;
+/* clang-format on */
+layout(location = 0) out highp float distance_buf;
+
+void main() {
+
+	distance_buf = depth;
+}