AllPlot: Add Reference Line for Power (Watts)
Read reference lines in WKO+ files

Added support for reading the 'references' or 'guide lines'
from a WKO+ ride file.
Add Derived Series to Ride Plot

You can now plot NP, xPower and aPower on the
ride plot.

This has been done to provide transparency &
insight into the relationship between the derived
values and the recorded power values,
Fix smoothing bug in Allplot for xPower and aPower
Fix crash on tmp reference line at 0w
User definable color for W' bal curve
UI Nits: Center Preferences/Options pane