#9126 Improve plot and curve handling for ensembles

Add append plots and append curves to context menu of ensembles
Make sure we create an unique color when adding multiple ensembles

ApplicationLibCode/Application/Tools/RiaColorTools.cpp

@@ -196,8 +196,10 @@ cvf::Color3f RiaColorTools::makeLighter( const cvf::Color3f& color, float normal
     double l = 0.0;
     qColor.getHslF( &h, &s, &l );
 
+    // A negative value will make the color darker
     l = l + ( 1.0 - l ) * normalizedScalingFactor;
-    l = std::min( 1.0, l );
+
+    l = std::clamp( l, 0.0, 1.0 );
 
     qColor.setHslF( h, s, l );