Do not unlock again if still in the app

[0x5ECF4ULT]

When configuring a schedule the app should not ask for ask for your passcode again when youre finished

[AlvaroBrey]

Currently, the app respects the "lock after" duration preference, whether you are still using the app or not.

Perhaps we can add a preference that will allow to bypass this if the app is open? This is, however, not as easy as it sounds, since Android doesn't provide an easy way to check if the app is open, and there are a lot of edge cases: screen off, app in background, phone off...