Implement review notes adding spark sim

[steersbob]

File: adding_spark_sim.md
Commit: 5be4c2c
Review date: April 12 2021
Tech: Tested on laptop with kubuntu 20.04 LTS and Spark (service: spark-one) with Fermentation Fridge wizard blocks (standard). Spark is powered & connected over USB. Spark simulation (spark-sim) was added as extra service.

l11: -added spark-sim simulation service-

l13: add a small story about the things you can and can't do with the Spark simulation service. What can you test? What can't you test?

l26: Situation: spark-one (real) and spark-sim (simulation) service running side-by-side. "Blocks and block names defined by a simulation service will not be used by a non-simulation service." - what does this mean?

• Both the DisplaySettings and the SparkPins block are listed in both services. - apart from system blocks?
• I can rename spark-sim simulation blocks to spark-one block names without error or loss of functionality
• I cannot link a real setpoint block to a simulation temperature sensor
  Conclusions:
• blocks of a simulation service can have the same names as blocks of real controllers
• blocks of a simulation service cannot be linked to real controller blocks
  Question: Can blocks be linked between two separate real controllers? Can a temperature sensor on spark-one be linked to a setpoint on spark-two?

l34: "The simulation blocks will be kept, but not used by the Spark controller." - what are the consequences? simulation blocks will be kept where? Why won't they be used by the Spark controller? Can you remove them? How?

-Testing Spark Sim Display widget-
File: all_widgets.md
Commit: 5be4c2c

-Created HERMS setup on Simulation Spark with HERMS wizard, all standard settings-

Spark Sim Display widget - black screen error:

1. HERMS dasboard -> create new Spark Sim Display widget -> define service (spark-sim) -> widget displays black screen, see SparkSimDisplayWidgetFirstLoad.png
2. weird on the service page the Display Settings Block has defined HLT PID, MT PID and BK PID but they do not show.
3. Force reload (Ctrl-F5) does not help.
4. Same behavior in Vivaldi browser.
5. brewblox-ctl restart fixed the issue.
6. Sill works after removing / re-adding the widget.
7. Widget black again after a visit to the service page list-view. Maybe important: toggled DisplaySettings block to full-view
8. brewblox-ctl restart fixed the issue again.
9. Cannot reproduce the behavior (black screen) by menu changes or reloading.
10. Behavior is reproduced by removing / re-adding the widget
11. Can reproduce 10. after brewblox-ctl update
12. brewblox-ctl restart fails to fix the issue
13. Widget works after reboot laptop
14. Keeps working after repeated reloading / menu changes
15. Behavior is reproduced by removing / re-adding the widget

Spark Sim Display widget - general:

• linking widget to spark-one service triggers a warning - good.
• Display standard footer text: "Edit this screen in the web interface" maybe better: "Edit this screen on the (simulation?) service page"
• Display brightness setting has no effect on widget
• Adding / removing a block from DisplaySettings does not remove the block color from the display - same behavior as real Spark