[Animations] Fixed a bug in the interpolator

include/ACGL/Animations/Interpolator.hh

@@ -78,7 +78,7 @@ public:
         }
     }
 
-    inline const T& interpolate(const float _progress)
+    inline const T interpolate(const float _progress)
     {
         //std::cout << "[LinearInterpolator] progress: "<<_progress<<std::endl;
 
@@ -127,7 +127,7 @@ public:
     {
     }
 
-    inline const T& interpolate(float _progress)
+    inline const T interpolate(float _progress)
     {
         unsigned int i = 0;
         for(i = 0 ;i < mKeypoints.size();i++)
@@ -187,7 +187,7 @@ public:
        // insert_control_point(data, 0.0f);
     }
 
-    const T& interpolate(float progress)
+    const T interpolate(float progress)
     {
         curve.insertKnot(progress);
         // TODO: Interpolation code is missing