Adds underwater circuit cables and a building where you can connect both wire colors to.

I wrote this mod with fulgora in mind, so distant islands can still communicate, e.g. what to load on trains and such.
(yes radars exist, but i want islands to communicate independantly without having to mix/alternate/bitshift any signals)

Everything on the same undersea data cable shares the same circuit network,
if you need to cross cables then just get them to shore and cross them there.

I am not entirely happy with how the shore based interface looks, but texturing is not my strong suit,
if you are an artist willing to help come up with a nice sprite that also covers up the cable going onto the shore let me know!