With popover usage now only passing in React Components, the
logic of removing the popover and recreating its html with
every update is not necessary. Instead allow React to update
the popover contents.

Because of this change, mouse event handlers are not recreated
on each update, so it is possible for mouseleave to fire after
the size of the popover shrinks when collapsing to hide more stats,
forcing the mouse out of the popover. To prevent this, padding has
been added to the top of the popover so on resize the mouse will
still be over the popover. The padding has the added bonus of
fixing an issue where the popover would not close until mouseenter
was triggered after size collapse, but it adds the drawback of
requiring more upward mouse travel to close the popover.

- Add a class to the body when in vertical filmstrip mode
- Override styles as necessary to support the mode
- Add an option to make tooltips display from the left
- Move the HD Label to the bottom left
- Move the remote video menu to the bottom left, move the mute
  icons to the bottom right
- Scale the local video's height and width to fit the filmstrip

All z-indexes found in css files have been moved into css
variables. If the z-index is used only once, the variable
name will be the same as the selector it is used in. If
the z-index is used multiple times, then the plain name
of $zindex# was used. This allowed a more confident
moving down of the toolbar so that the new modal dialog,
with z-index 500, could display on top of it.

#1436

This reverts commit 93648f361b.