Ability to keep a left menu exposed on larger viewports, such as a landscape tablet. Added the `expose-aside-menu` attribute directive.
When a list was within a side menu it could scroll up and down, but if the user happened to drag a little bit on the X axis, then it would try to open the side menu and the Y scroll of the content stopped. Closes #1541
edge-drag-threshold
edgeDragThreshold()
Closes #1570