Shade Selector on CP chart

- none - no shading on the all curve
- derived CP - as before using the CP value derived from all curve data
- CP - the value of CP for the time of the ride

NOTE: When in rangemode (i.e. on home) the CP is set to the mean CP for
the date range selected.
Fixup last commit

.. strange edits lost related to widget layouts.
UI Nits: Add titlebar for splitters
Correct : splitters not resizing after expanded