Gestures continue instead of restarting: everything that follows a drag now settles on
a critically damped spring handed the velocity the finger left behind, where a tween
had accepted that velocity and ignored it. One detector owns both axes of a surface
that can be swiped and dismissed, a pager that has stopped moving stops calling itself
a scroll, and content resists where there is nothing to reach.

New: a rising page a finger can hold anywhere, stackable over another rising page and
dismissable by the list inside it; a page dragged between its neighbours; a long list
whose rows are picked up by holding and swiped out sideways; two chevron icons.

Additive only: every change is a new parameter with a default or a new declaration, so
a call written against 1.0.0 or 1.0.1 compiles unchanged.