drupal 4.6.0 compatibility patch

The attached patch adds drupal 4.6.0 compatibility to the image_filter module.

• Uses the files table instead of the image table
• Does not rely on the image module scaling feature, which no longer exists in the 4.6.0 version. Instead, if a height or width is specified, it finds the next larger image file and uses the img tag's height and width attributes to instruct the browser to scale the image.
• Always produces height and width attributes for the generated img tag to allow the browser to render the page faster.
• Adds a size=name option as an additional way to specify the image size, for example size="original".
• Adds a nolink=1 option to disable the link to the image node.

However, one way that the new code is not as good as the old code is that it performs a select for each image instead of one select for all the images.