Use Chrome Frame when available, and ask to install it

[sander]

If most Internet Explorer 6, 7 and 8 users would have Chrome Frame installed, we could use some nice HTML5 and CSS3 features.

I suggest we also try to prompt our IE users (23%) to install the plugin. It would look as ugly as in the attached screenshot, but may be worthwile and we can quickly remove it again.

http://www.google.com/chromeframe

http://pleft.googlecode.com/issues/attachment?aid=-2637588941607814838&name=chrome-frame-popup.png&token=UFx5eqsXYuRsbdCEfCqVd6MitlA%3A1324763348087&inline=1

Simple patch that does this.

http://code.google.com/p/pleft/issues/attachmentText?id=23&aid=-5438436004275980608&name=chrome-frame.patch&token=cuHFGFFgxp68fhnzxBLv9oGZWLE%3A1324763348088

First step done in hg revision 7c85323690: only the popup isn't shown yet.