Issue: As step size was hard coded in the widget, when slider indicator is dragged
using a key event or during accessibility the value was not exactly incremented/decremented
instead same value was shown more than1 time/values were skipped.
Solution: Two APIs added which will set/get step size.
Reviewer: SeoZ
Reviewer Comment: This is a manual merge of D293 due to arc issue on Shilpa.
I modified some codes from her original code. She'll use arc next time.
fixed documentation
fixed typos.
fixed indentation
used macro
added some guide codes.
removed unnecessary empty line.
updated NEWS and ChangeLog.
Yakov Goldberg
Anil Kumar Nahak
Daniel Juyung Seo
Daniel Zaoui