Add Watts/Kg in the cpx cache files and in the CP plot

modified:   src/CpintPlot.cpp
	modified:   src/CriticalPowerWindow.cpp
	modified:   src/CriticalPowerWindow.h
	modified:   src/HistogramWindow.cpp
	modified:   src/RideFile.cpp
	modified:   src/RideFile.h
	modified:   src/RideFileCache.cpp
	modified:   src/RideFileCache.h

src/HistogramWindow.cpp

@@ -213,6 +213,7 @@ void HistogramWindow::addSeries()
 {
     // setup series list
     seriesList << RideFile::watts
+               << RideFile::wattsKg
                << RideFile::hr
                << RideFile::kph
                << RideFile::cad