[Design] Sidebar icons

[Sheila Mooney]

We have made quite a few changes to the sidebar icons in response to  
user feedback since 0.6 was released. We are pretty happy with the  
current design and feel it addresses many of the user concerns and is  
a good compromise with the tools/widgets available. As a result, we  
won't be iterating further on the sidebar icons for Preview and will  
be focussing our attention on application stability, performance and  
completing the remaining key features.

Cheers,
Sheila