Added simplification back for quicker preview renders with less subdivision

levels, child particles, and shadow/SSS/AO quality.. Now also works on what
is displayed in the 3d view instead of only rendering, see panel in the scene
properties.

Most file changes were to make scene available in the isDisabled modifier
callback function.

release/scripts/ui/properties_scene.py

@@ -180,11 +180,40 @@ class SCENE_PT_physics(SceneButtonsPanel):
         else:
             layout.column().prop(scene, "gravity", text="")
 
+class SCENE_PT_simplify(SceneButtonsPanel):
+    bl_label = "Simplify"
+    COMPAT_ENGINES = {'BLENDER_RENDER'}
+
+    def draw_header(self, context):
+        scene = context.scene
+        rd = scene.render_data
+        self.layout.prop(rd, "use_simplify", text="")
+    
+    def draw(self, context):
+        layout = self.layout
+        scene = context.scene
+        rd = scene.render_data
+        wide_ui = context.region.width > narrowui
+
+        layout.active = rd.use_simplify
+
+        split = layout.split()
+
+        col = split.column()
+        col.prop(rd, "simplify_subdivision", text="Subdivision")
+        col.prop(rd, "simplify_child_particles", text="Child Particles")
+
+        if wide_ui:
+            col = split.column()
+        col.prop(rd, "simplify_shadow_samples", text="Shadow Samples")
+        col.prop(rd, "simplify_ao_sss", text="AO and SSS")
+
 bpy.types.register(SCENE_PT_scene)
 bpy.types.register(SCENE_PT_unit)
 bpy.types.register(SCENE_PT_keying_sets)
 bpy.types.register(SCENE_PT_keying_set_paths)
 bpy.types.register(SCENE_PT_physics)
+bpy.types.register(SCENE_PT_simplify)
 
 bpy.types.register(SCENE_PT_custom_props)