Bugfix, complication (details below) (#238, #271, #290)

Original problem: feedback wasn't engaged when economizer wasn't configured
due to a typo

Collateral: feedbackFlux is not closed, this is why test cases stall.  Fix
is in the next commit.

dz3r-model/src/main/java/net/sf/dz3r/model/Zone.java

@@ -202,7 +202,7 @@ public Flux<Signal<ZoneStatus, String>> compute(Flux<Signal<Double, String>> in)
 
         var source = Optional.ofNullable(economizer)
                 .map(eco -> eco.compute(combined))
-                .orElse(in);
+                .orElse(combined);
 
         // Since the zone doesn't need the payload, but the thermostat does, need to translate the input
         var stage0 = source