This version is probably the easiest rollover version to implement
It relies on placing the 'onmouseover' directly on the image, instead of on the <a> tag.
This allows the use of the keyword 'this' to identify the image, instead of relying on an image name.
In this version, the images do not have a name or id, to demonstrate.
The body's onload event handler passes a set of image names, without the path, which is specified in a global variable.
The image path is stored in a global variable (imgpath) that is in scope in both functions, preload(), and rollover() respectively.
Any number of images can be preloaded and the arguments of the preload() function are a property accessed in the form of an array.
