"core" change: color property interface fix

(cherry picked from commit ad722d98127144e0ff34523f210247a92f8dbb20)

core/properties/colorproperty.h

@@ -47,8 +47,8 @@ namespace campvis {
                 const std::string& name,
                 const std::string& title,
                 const T& value,
-                const T& minValue,
-                const T& maxValue,
+                const T& minValue = T(0.0f),
+                const T& maxValue = T(1.0f),
                 const T& stepValue = T(0.01f));
 
             static const std::string loggerCat_;
@@ -64,9 +64,9 @@ namespace campvis {
         const std::string& name,
         const std::string& title,
         const T& value,
-        const T& minValue,
-        const T& maxValue,
-        const T& stepValue) 
+        const T& minValue = T(0.0f),
+        const T& maxValue = T(1.0f),
+        const T& stepValue = T(0.01f))
         : Vec4Property(name, title, value, minValue, maxValue, stepValue)
     {