WPK metrics need 2 decimals not 1
RideFile(RideFile*) can set context too

.. so no need to do it everywhere we create a temporary
   ridefile for computing metrics.
Lactate not Lactic Threshold

.. just being picky now.
Fixup Compare to Use RideFile(Ride*)

.. to get CP and Weight tags etc
CPPlot Show Best Option

.. sometimes its useful just to see the model and not the bests
   curve. So added an option to get rid of the bests curve and
   show the model on its own.