ENH: Add Orange color

This is needed for the VROrthognathic/OrthognathicTrainer project.

Source/Core/imstkColor.cpp

@@ -38,6 +38,7 @@ Color Color::Blue(0.0, 0.0, 1.0, 1.0);
 Color Color::Green(0.0, 1.0, 0.0, 1.0);
 Color Color::Red(1.0, 0.0, 0.0, 1.0);
 Color Color::Yellow(1.0, 1.0, 0.0, 1.0);
+Color Color::Orange(1.0, 0.6, 0.0, 1.0);
 Color Color::Pink(1.0, 0.0, 1.0, 1.0);
 
 Color::Color()

Source/Core/imstkColor.h

@@ -100,6 +100,7 @@ struct Color
     static Color Green;
     static Color Red;
     static Color Pink;
+    static Color Orange;
     static Color Yellow;
 };
 }