Implement screen for the cube settings

[akosgarai]

An example application has been implemented: akosgarai/go_opengl_playground#163
The issue: akosgarai/go_opengl_playground#157

Now it comes to implement it in the engine.

Improvements

• The middle monitor has to contain a button for camera setup.
• The middle monitor has to contain a button for lightsource setup.
• The camera and lightsource setup should happen on the left monitor.
• The middle monitor has to contain option for adding objects to the screen.
• The object setup should happen on the right monitor.