Update Scene tree editor also while EC editor is open
Represent enum attributes with a combobox / select element to avoid putting invalid values
Add TransformEditor class, which will take care of the entity containing TransformGizmo
Re-implement XML3D part for Entity and Component: An XML3DElement 'inherits' both EntityWrapper and ComponentWrapper, since it can be either of those; Added Up button to go up the hierarchy in case of XML3D; Added 'Edit' button for each child of an XML3DElement; Consider also the available child elements when creating an XML3DElement; Various tiny UI fixes