PfPvWindow: Add Compare Mode
CriticalPowerWindow: small correction
ExtendedCriticalPower: Add contribution curves eCP version 6
PfPvPlot: Fix Color for intervals
PfPvPlot: Correct last commit
CpintPlot: hide contribution curves
Fix allplot Compare mode refresh

.. if you selected a ride and viewed on allplot then
   changed tabs, entered compare mode then switched back
   to allplot the display didn't get refreshed.
Disable reference lines in compare mode

.. it has nowhere to save them.

.. we could reintroduce and save with a compare set
   when we have one of those!
merge upstream into master