Beginning to address #726: ECEditorWindow: add ECEditorWindow::AddEntity(EntityPtr), add and use new signal that uses EntityList instead of single EntityPtr for signaling changes in entity selection. Gives some minor perf increase but nothing significant. Use static_cast over dynamic_cast where applicable. ECBrowser: Entities return EntityList instead of QList<EntityPtr> and SelectedComponents return std::vector<ComponentPtr> instad of QObjectList (these are what Scene & Entity APIs deal with so more naturally choice (+exposed to script properly so should not break things). Add SceneStructureModule:Scene function.
Now that rex Tundra 2.5.1 and deprecation warning for 'scenestruct' console command is out, remove the deprecated command.