- added settings for sunrise/sunset,day,night,sensor auto switch
- DayNightHelper contains the base switching logic
- auto switching works only if render is selected which has its -night counterpart
- light sensor threshold is currently hard coded
git-svn-id: https://osmand.googlecode.com/svn/trunk@854 e29c36b1-1cfa-d876-8d93-3434fc2bb7b8