uix: ScrollView change usage of scroll_type to use a list make the
option more future proof, update scroll position when mouse wheel is
used to scroll, make scrollview scroll differently depending on which
bar mouse is on when mouse wheel is used.
update scroll on next frame instead of waiting 1 sec
uix:ScrollView fix comparison thanks for the suggestion Ian.
Merge pull request #1626 from kivy/scroll_view

Scroll view: change usage of scroll_type to use a list make the option more future proof