Added animations; plus performance fix

- Eps images are not re-rendered on every goemtry change anymore, but
just when the scale changes. Therefor resizing the window works with
decent speed again.
- There is some code to animate changes in the worksheet. I am not yet
quite sure which changes should be animated so that the experience
is consistent and the user is not annoyed by too many (slow)
animations. But I think that the animations can improve the
experience of the user.