Searchbar

Hi Stef !

This pull request does two things about the busy icon in the searchbar:

- the animation timer is only started when a search starts, and is stopped when the search finishes. This avoids having a timer constantly firing... (Ideally having no timer firing would be great to save battery on a laptop, and I guess it can also help for users of Icy on small machines  - I was almsot crying when I tried using Icy on my eeepc !)

- Improve the look of the busy icon by increasing its rate to 50Hz and decreasing the dot size.

These commits are pretty safe, I think you can safely pull them. Thanks !