Reorder components via drag-drop

In 'Edit' mode, existing components in containers can be reordered via drag-drop. They can be moved within a container or to other containers. Doing so only re-renders the changed containers.

The 'mirror' of the component (the dragged representation) should be rendered in the app instead of the site, so it will also be shown outside the border of the iframe. This makes dragging a component in Tablet and Phone view nicer, since the mirror won't be cut off by the sides of the iframe.