String.prototype.hilite

@Description: Hilites a string within a text block
@File: String/prototype/hilite.js
@Author: Paul Visco
@Version: 1.1 05/29/07
@Param: String needle The text to find
@Param: String className The className to use for hiliting overrides default yellow background style
@Return: String witht he needle underlied and hilited
@Example:

var myString = 'There was a dog on earth';

var newString = myString.hilite('dog');
//newString = 'There was a <u style="backgroundColor:yellow;">dog</u> on earth';