Removed $.browser references for #907

1. **equalheights.js**: removed IE6 support.
1. **bookmarks.js**: replaced with feature detection, CSS changes and removed pre FF 1.9 support.

If you'd like, I can submit a pull to the [bookmark repo](https://github.com/kbwood/bookmark), but I'm not sure if it'll get merged.  @nschonni's from 3 months ago is still open .