Add the range selector code to the overview chart

This needs wiring up correctly and it could be animated with POP instead
of manually?
Removing some commented-out lines

No longer needed now we're using the range annotation
Refactored the range annotation to get an idea of when it has stopped

We only want to refresh the data once it has stopped moving, otherwise
it might be a little intense.
Added methods to the data layer to extract data within a date range

Rather than restricting it to a quarterly basis