[TiM's osC Solutions] Cached image thumb

for osCommerce Online Merchant v2.2

This contribution gives you the following features: * Cached thumbnails in catalog for faster loading times. * Tweakable for having thumbnails created with a transparent backgrounds. * Saves cached thumbnails in a separate folder (easy for cleaning up). * Unique md5 thumbnail filenames such as e0f8ab89c52355e107326293f64e6f25_100x80.jpg based on md5("path/to/file.ext"). Caution! This may collide with other image management contributions.