Added feature to open top most tab on pressing <enter> in the search box

Hi,

First of all, thx for the extension :)

I added a simple feature to go to the *top most tab* in the tab list (div id='tabs') when <enter> is pressed in the search box. I'm using your extension with this new feature.

Thought, you might interested to add it to your version.

Thx for the extension again,
KR,