Low-end devices need help!

-> Check for wakelocks faster
-> More granular hidden apps selection
-> Kill hidden and service_b apps at higher lmk
-> Rearrange OOM values [similar to SuperCharger! But not exact]
Smoother Lockscreen framework on Low End devices

Devices with less than 512 MB 'usable' RAM
Remove unnecessary locking for screen broadcasts.

The actual handling occurs in updateScreenOn() on the other side of a
handler, which acquires the lock correctly.