Add an option to enable FLAG_ALLOW_LOCK_WHILE_SCREEN_ON so the device can be be locked.

[vindolin]

On Android the device doesn't lock when the power button is pushed and an app with FLAG_KEEP_SCREEN_ON runs in the foreground.

Adding the FLAG_ALLOW_LOCK_WHILE_SCREEN_ON flag in addition to FLAG_KEEP_SCREEN_ON, makes it possible to keep the screen on when the app is running and still lock the device when the power button is pressed.

[lynrin]

Hi, @vindolin

Added support for FLAG_ALLOW_LOCK_WHILE_SCREEN_ON as v3.0.0.
try it.