Caches everyone's username and displayname. Then changes {displayname} to @username. It will also update the displayname if it gets changed.
Note: Has not been extensively tested on large forums. Also, there are certain characters that are not valid in a regular expression, if a user has these characters in his name, you will not be able to do {displayname} and get his usernmane because the code doesn't understand his displayname. The rest of the displaynames will still work though. ( you cant type these special characters anway so it shouldn't really make a difference )
