Links with !s in the url not working

[faceless]

Twitter and Google groups use !s in their urls, but that character doesn't display properly if used in a link here. To get past this problem replace the ! with %21 and the links will work.

Here's an example - this doesn't work

https://twitter.com/#!/

but this does

https://twitter.com/#%21/


Similarly, if a link has a ( or ) in it, replace those with %28 and %29