Fast-replace arithmetic and decider combinators

[caudate_julie]

What?

Allow fast-replacing for arithmetic and decider combinators while keeping the wires

Why ?

Arithmetic and decider combinators have the same size and the same set of outputs. Quite often you want to have different operation with the same inputs, like:

Before:
decider: A > B => output 1 C

After:
arithm: A - B => output as C

It would be much easier to replace the combinator and change only operations, but not rewire it, especially since wiring can be quite messy.

[eradicator]

It would be much easier to replace the combinator and change only operations, but not rewire it, especially since wiring can be quite messy.

It would also be much easier to copletely mess up your circuitry with a single click. I believe the current implementation is a protection mechanism against that. Should be easy enough to change it in a mod though.

[conn11]

Fast replace probably isn't the best idea, but what about integration into the upgrade planner? This would effectively circumvent messing up builds by mere chance and since rail signals are interchangeable with chain singnals why not combinators (excluding the constant combinator of course).

The only question remaining is how to handle the different set of operators. Just picking the default one (as you would, when placing a new combinator) seems the most straight foreward solution.
But this leaves us with the question, how easily players would get confused by such a setting and how practical it would actually be, given that chainging the operatores would remain a manual task (given with an intact wirering).

[Hares]

Since we are getting a third combinator in 2.0 I see this feature request as a must.