Removed _change_notify

-For inspector refresh, the inspector now detects if a property change by polling a few times per second and then does update the control if so. This process is very cheap.
-For property list refresh, a new signal (property_list_changed) was added to Object. _change_notify() is replaced by notify_property_list_changed()
-Changed all objects using the old method to the signal, or just deleted the calls to _change_notify(<property>) since they are unnecesary now.

scene/resources/style_box.cpp

@@ -123,7 +123,6 @@ void StyleBoxTexture::set_texture(Ref<Texture2D> p_texture) {
 	}
 	emit_signal("texture_changed");
 	emit_changed();
-	_change_notify("texture");
 }
 
 Ref<Texture2D> StyleBoxTexture::get_texture() const {
@@ -135,13 +134,6 @@ void StyleBoxTexture::set_margin_size(Side p_side, float p_size) {
 
 	margin[p_side] = p_size;
 	emit_changed();
-	static const char *margin_prop[4] = {
-		"content_margin_left",
-		"content_margin_top",
-		"content_margin_right",
-		"content_margin_bottom",
-	};
-	_change_notify(margin_prop[p_side]);
 }
 
 float StyleBoxTexture::get_margin_size(Side p_side) const {
@@ -228,7 +220,6 @@ void StyleBoxTexture::set_region_rect(const Rect2 &p_region_rect) {
 
 	region_rect = p_region_rect;
 	emit_changed();
-	_change_notify("region");
 }
 
 Rect2 StyleBoxTexture::get_region_rect() const {