Feature: Gutter with arrow icons to move either left/right or top/bottom with one click. #163

Thanks for this awesomely simple-to-use lib.

Is it good to have optional left/right or top bottom icons (with click) which will cover the entire split-area based on click?
E.g. the gutterClick example, the click (anywhere on gutter) will cover the split-area based on the clickHandler logic. Instead, click on optional icons will cover that area.