.. Connected the compare mode on/off switch in the
compare pane to Context to notify charts
.. the scope bar and chart painting now highlight in
red when compare more is active and supported by
a particular chart.
.. each chart must implement isCompare() to return
true or false if it is supporting compare mode.
We /still/ do not have a mechanism for clearing or
reordering items in the compare pane, nor a mechanism
for choosing 'delta' compare (i.e. baseline all compares
to first item in the list).
.. now can drag and drop any date range onto the
home view compare pane to compatre different
seasons, and even across athletes.
.. we setup the metrics and measures in the context
so the charts don't have to, but we still need to
reference the source context for bests and ridefilecache
data
NOTE: We need a mechanism for 'locking' source tabs/athletes
when they are part of a compare to avoid crashing when
a context is deleted whilst we are comparing
NOTE: We till need a way to remove entries from the compare
pane, possibly call it when an athlete is closed too
(see note above).
Slowly migrating code and data from the MainWindow
class to Athlete and Context classes.
This update moves the ride and interval lists and
data structures from MainWindow to Athlete.
