Correct the desired width for Adium's tabs from double counting the icon and close button.
AdiumTabStyle: Scale the icon for the maximum width allowed.
-convertRectToScreen is not available on 10.6.
AdiumTabStyle: Enforce a width for the large image.

This keeps the text lined up and better centres the image.
AdiumTabStyle: Try to use the unofficial source list background colour for vertical tabs' background.
Merge pull request #33 from wixardy/master

Fix some issues with Adium's tabs