Initially implement a synchronized pan/zoom stack,
which maintains the same domain axis bounds for all
subplots in a stacked plot view, but allows each to
have independent range axes. WTD-625.
Fix issues related to refactoring of view-level
to subplot-level behavior, such that previous
functionality is restored. This refactoring
supports introduction of a stacked-plot mode,
for WTD-625.
Begin refactoring Plot view to support stacked plots;
separate out behavior which needs to occur per-plot
from area which should occur per-view, and add a
handler for the Overlay mode. WTD-625.
Get/set mode from the plot mode switcher; only show
the switcher if there is more than one mode available
(which should only occur when there is more than one
telemetry object in the plot.) WTD-625.
