Overhaul auto-brightness level UI.

This changes a few things:
- Don't imply a 'bucket' type of algorithm is used by showing an ambient
  brightness range for each line
- Allow manually entering the screen brightness
- Add a preview window for the cubic spline interpolation
- Add a help text

JIRA:CYAN-612
Change-Id: I64274280872b9fe4f6fdc368d654aca81e0a4e0c

Conflicts:
	res/values-af/strings.xml
	res/values-da/cm_strings.xml
	res/values-de/strings.xml
	res/values-el/strings.xml
	res/values-es/strings.xml
	res/values-fr/cm_strings.xml
	res/values-hu/cm_strings.xml
	res/values-it/cm_strings.xml
	res/values-ja/strings.xml
	res/values-ko/strings.xml
	res/values-nl/cm_strings.xml
	res/values-pl/cm_strings.xml
	res/values-pt/cm_strings.xml
	res/values-ru/strings.xml
	res/values-uk/strings.xml
	res/values-zh-rCN/strings.xml
	res/values/cm_strings.xml
	res/values/dimens.xml