have wires stay connected if possible when changing node data type

Often I drop down a mix node, connect the noodles, and then realise I have the mix node set to float instead of colour. When I change the datatype from float to colour, all noodles are disconnected (they're actually still connected to the old no longer visible socket)

I propose that the hidden sockets remain wired (for coding purposes), and the same links are copied from the previous sockets to the new sockets where possible. For example the mix node always has fac, A, and B sockets regardless of which data type is chosen in the dropdown.