row-reverse and column-reverse do not overflow correctly in Firefox.
The left side's statblock list is now row-order; the list of combatants
is reversed, and the list is automatically scrolled to the right

Each wheele vent restarts the smooth-scrolling. It will need
to keep track of where it's scrolling to.

Also cleans up some old duplicate code that I made, somehow.

Containers can now offer actions to their contents.