[Pharo-project] ThemeSettings>>#menuSelectionColor: should return self

I was playing with the new Pro theme, and this bit me hard (crashed my image several times before I found out why): ThemeSettings>>#menuSelectionColor: should return self not a Color, just like all other setters, otherwise the cascades in UITheme class>>#newDefaultSettings won't work, although a final #yourself would be good style there too. Sven