[1/2] Base: On-The-Go mode

On-The-Go turns on the camera of your phone and streams it to an overlay,
which is drawn over everything.
this makes you feel like your display is transparent, as you see the content
behind it.

its really useful when you are using your phone while walking, thats why
we called it "On-The-Go"

allows to change transparency of the overlay via the notification.

have fun!

rewrite and tweak de service

add Tile

drawable courtesy of @Alex-Cruz thanks :)

also fix possible NPE

PS11: rebased
Conflicts:
        packages/SystemUI/src/com/android/systemui/statusbar/phone/QuickSetting$

Change-Id: I149e3578e51d9b8b8c8bff41c4eaebca774739ab

Conflicts:
	core/java/android/provider/Settings.java
	core/java/com/android/internal/util/omni/DeviceUtils.java
	core/res/res/values/custom_strings.xml
	core/res/res/values/symbols.xml
	packages/SystemUI/AndroidManifest.xml
	packages/SystemUI/res/values/custom_strings.xml
	packages/SystemUI/src/com/android/systemui/statusbar/phone/QuickSettingsModel.java
	policy/src/com/android/internal/policy/impl/GlobalActions.java