New url_helper anchor tag that allows for an image link

[eluser]Aken[/eluser]
Should be useful for those people who are still having trouble grasping how to pass an image to the anchor() function.

There are some things I would recommend cleaning up / changing, if you're interested in hearing them. Don't want to just list them off because people usually think I'm a jackass when I do that, even though they're suggestions on how to better the code.