Image sequencing improvements and optimization of projection.

Projection now occurs only at specified timestamps.
Todo:
projection class now dependent on image sequences, will have
to change that once we read specific instrument schedule.

src/engine/openspaceengine.cpp

@@ -499,7 +499,7 @@ void OpenSpaceEngine::preSynchronization() {
         _interactionHandler.update(dt);
         _interactionHandler.lockControls();
 
-		Time::ref().advanceTime(dt);
+	//	Time::ref().advanceTime(dt);
     }
 }