Delete key in layout attempts to delete read-only links

[blondejamtart]

No description provided.

[blondejamtart]

storm-react-diagrams has a delete behaviour for links and blocks, which we set which keys trigger it and also hook in to fire the messages to malcolm to actually remove the link (without this the link will just be removed from the local layout state but will be redrawn once any update to the layout is received). Currently, we check if the layout is writeable and unbind the delete keys from the layout if it is not. Since storm-react-diagrams will (as standard) delete the link before our hook can check whether or not it is writeable the best solution may be simply to force a redraw of the layout if any links on which delete was called were not writeable.

[blondejamtart]

On closer investigation, it looks like we are no longer hooking into the delete behaviour of storm-react-diagrams, so we can disable it completely; this will impact how/when links and blocks disappear from the rendered layout upon deletion to a minor extent.