Allow connections to be made between pins

[andrewdavidmackenzie]

Describe the solution you'd like
Allow connections to be made, so a connection on the GUI could be "drawn" between an input and an output.
e.g. used presses a button (input) and an LED is lit (output.

You could also allow for some "transformations" on the connection, like inverting etc....

Additional context
Could expand massively to be a logic design UI, which not sure we want to do.