The tutorial 99% works, but the DisplayTutorial with the callbacks has
a strange issue during setup.
Likely photon specific.
When it boots, nothing is displayed on the screen. Totally black.
It should say "None pressed"
And I clearly see you calling onButtonRelease() in setup.
If I push buttons after that, it works fine, and when released, it properly
says None pressed.
If I add an init flag, and call onButtonRelease in loop(), it works.
If I directly set screen in setup, it does nothing.
Adding a few Modulo.loop() or Particle.process() did not help.
So something about being in setup() not loop() makes display not work.