Drawing does not work on title slide

[monofon]

Drawing on the title slide does not work if the title slide is the first slide that is displayed, eg. by opening the deck without a slide id fragment. These URLs provoke the bug:

• http://localhost:8888/topics/000-introduction-deck.html
• http://localhost:8888/topics/000-introduction-deck.html#/title-slide

Opening the deck on any other slide and then navigating to the title slide works.

[salbeira]

Commit in fix-whiteboard-first-slide should resolve this issue. Please review.