Hand drawn mockups for 3.1 MainWindow options

Playing with some ideas about how the UI will change
to support new UX features for viewing multiple athletes
in a single mainwindow and also having multiple pages
of charts in a single view.

2 Options on the drawing:
.. Having tabbed Athletes and scope bar for view pages
.. Having a source list and tabbed view pages

Can't decide which is best -or- if there are better options
we could look at.