[0.17.79] Hold mouse button to "paint" copper/red/green wire connections

[JasonC]

It would be extremely useful if, when a wire item (copper, red, or green) was in hand and the mouse button was held down, moving the cursor over an entity connected the wire to that entity.

This would be super convenient in a lot of situations, e.g. when wiring up groups of chests or inserters, or when wiring circuit networks along train tracks while riding in a train, things like that.

The behavior when dragging the mouse over entities should be almost exactly the same as clicking each of those entities one at a time in the order you drag over them, except without the "disconnect" action when you drop a wire over an existing connection.

Edit: Added note about disconnect action.