[1/4] framework: custom brightness support

Adds separate handling of button brightness for devices
that supports it. Enabled with config_button_brightness_support
else the behaviour will be the same as before

Also if enabled but no custom values are set will fallback
to the previous behaviour

This also needs support of setting button brightness separately
in liblights code of the device.

Options:
-brightness spline for buttons in automatic mode
-custom brightness value for buttons in manual mode
-options to competely disable buttons in both modes
-option to always fallback to same value as screen brightness

This also brings in:
-support for custom responsivness value for automatic mode
-custom twilight support enablement

PS2:
-added API for settings

PS4:
-whitespace cleanup

Change-Id: I37535de80bd30936319f3e2535e991f7c6c195c1
Merge "[1/4] framework: custom brightness support" into android-4.3
[1/2] base: add CPU info overlay

this shows
CPU temp (if available)
for every core governor + online + freq

PS3:
increased font size

PS4:
whitespace cleanup

PS5:
more of that :(

Change-Id: I8e2fd81edd8499eea2b1a6de8c042938387b33ef
Merge "[1/2] base: add CPU info overlay" into android-4.3
base: cleanup missed whitespace problem

Change-Id: I1494abaa28bc3297b8c47684e83d0a701d4e33d4
Merge "base: cleanup missed whitespace problem" into android-4.3