Summary

Maintain all event layer visibility states separately,
All buttons of event layers are working with their state and preserved in localStorage state.
Remove all global state of visibility and remove all related codes
'd' button is still usable
remembers all labels state and works correctly with the output minimal
correctly works with movie and screenshot makers, handle them as before

Testing

Enter the browsers and the output modes (minimal, normal, embed) this change was tested

browser	normal	minimal	embed
firefox	untested	untested	untested
chrome	tested	tested	untested
safari	untested	untested	untested
edge	untested	untested	untested