Prevent cheating by turning screen off

[omahlama]

Turning screen off stops the ghosts but keeps the timer running. Possible fix:

• freeze timer when screen is off
• when screen is back on, teleport ghosts so they are at the same position relative to the user as when screen was turned off.

[oasalonen]

Duration is incremented now during every engine tick event. This should at least stop the accumulation of time while the app is dormant.

However, it is not the best way since it assumes that the game tick is fired off at exact intervals. Better would be a way to detect when app is dormant and accumulate a pause time, then subtract the pause time from the duration calculated from the difference of the game stop and start time.

I also disabled application idle mode detection while game is running. Not sure if this does what I intend, need a device to verify.