Further trackpad work:

When trackpad swipes don't convert to ScrollWheel steps anymore, several hardcoded
wheel events need to support swipe too.

This adds swipe support to:
- Menu item scroll
- Search item scroll
- ALT + number/slider/swatch values

The amount of old style scroll "clicks" is calculated based on how trackad is
being mapped to move a mouse pointer. Move it one widget unit = 1 click.

The swatch option applies trackpad swipe motion in analog way.



git-svn-id: https://svn.blender.org/svnroot/bf-blender/trunk/blender@53487 954f8c5b-7b00-dc11-b283-0030488c597c