Refactor the DVD Controller

[kmcurry]

The "DVD Controller" is responsible for play, pause, stop, fast forward and rewind of animation in the 3D scene.

The UI is currently buried on the Slides tab of the sidebar panel (line 578 in create.ejs).

Group the button elements into a div with id="DVDControls" and move the div to sidebar panel so that the controls are always visible on the panel when it is open. They can go above the tabs ("Objects", "Slides").

While testing:

• Load Egypt, Two-Stroke and Light and confirm the control works as expected
• Animate some objects and confirm the control works as expected
• Report unexpected behavior in the comments below

In the future:

• We'll reuse the controls on other panels or ui configurations.

[kmcurry]

Possibly move DVD control