Limit the rate manage_heater() as it did previously

Avoid running the user-level error handlers too fast.

Firmware/temperature.cpp

@@ -485,8 +485,12 @@ void manage_heater()
     wdt_reset();
 #endif //WATCHDOG
 
+    // limit execution to the same rate as temp_mgr (low-level fault handling is already handled -
+    // any remaining error handling is just user-facing and can wait one extra cycle)
+    if(!temp_meas_ready)
+        return;
+
     // syncronize temperatures with isr
-    if(temp_meas_ready)
     updateTemperatures();
 
     // handle temperature errors