Finalized user interface for Transition View. Cleanup DrawVisitor was

needed. New ImGuiToolkit functions implemented.

RenderingManager.h

@@ -132,9 +132,10 @@ public:
 
     // get projection matrix (for sharers) => Views
     glm::mat4 Projection();
-    // unproject from window coordinate
+    // unproject from window coordinate to scene
     glm::vec3 unProject(glm::vec2 screen_coordinate, glm::mat4 modelview = glm::mat4(1.f));
-
+    // project from scene coordinate to window
+    glm::vec2 project(glm::vec3 scene_coordinate, glm::mat4 modelview = glm::mat4(1.f));
 
 private: