Improve brightness curve preview

- Avoid log spamming
- Add a little margin around the grid so outer control points aren't cut

Change-Id: Idb6cd2773186f9e7011486dc62f21e2fab85e245
Re-add auto brightness configuration UI (2/2).

Change-Id: I6c56a48fa2145c58a5f203ed56051451ef3f977d

Conflicts:
	AndroidManifest.xml
	res/values/cm_strings.xml