Fluid Tank circuit modes: Read/flush network

[Mylon]

TL;DR

Extend the new fluid controls to make them accessible via circuit.

What ?

The means to read the fluid network already exists in the entity detail popup. The ability to flush fluids via this method also exist. Make them available for circuits.

Why ?

These functions exist already. It shouldn't be too hard to add an additional means of triggering them. It also gives players the ability to add alarms, automate fluid voids, and accomplish other neat features via use of circuits. Like one tank can do read, a combinator does if light oil > 0 output red signal, and another tank does if red signal > 0 then flush light oil to automatically remove contaminants.