Adds custom highlights for the "Silver Lining" color theme of gmail2, basically making it darker overall.

Close to Gmail's "Contrast Black" theme, which I don't use because I think the yellow links color just doesn't work.

Before Shot:
http://www.divshare.com/img/6440449-f17.jpg

After Shot:
http://www.divshare.com/img/6440448-dec.jpg

Dev notes:
---------------
2009-Jan-30
Pardon poor documentation / lack of acknowledgements; this is very much w-i-p.
As you can see from the before/after shots, the font colors need improvement!
****** Can anyone help with this please? ******