Suggestion: indicate non-functional pipes on plumbing overlay

[chromiumboy]

So last night I spent quite some time pulling my hair out trying to fix my sanitation system, which had been working smoothly for many cycles then suddenly ground to a halt (I figured that out when my dupes started peeing themselves).

For a while I thought there was a bug preventing sand being delivered to my filtration plants. Then I spotted my problem: a single piece of pipe had been accidently deleted during my recent base renovations

My suggestion is that non-functional / incomplete pipe systems be highlighted on the plumbing overlay screen in somw way, similar to how wires not receiving power are a different colour on the electrical overlay.