-Many fixes to VisualScript, fixed property names, etc.

-Added ability to set/get a field in GetSet, as well as assignment ops
-Added a Select node
-Fixed update bugs related to variable list and exported properties, closes #9458

editor/property_selector.cpp

@@ -167,7 +167,7 @@ void PropertySelector::_update_search() {
 				continue;
 			}
 
-			if (!(E->get().usage & PROPERTY_USAGE_EDITOR))
+			if (!(E->get().usage & PROPERTY_USAGE_EDITOR) && !(E->get().usage & PROPERTY_USAGE_SCRIPT_VARIABLE))
 				continue;
 
 			if (search_box->get_text() != String() && E->get().name.find(search_box->get_text()) == -1)