Rebuilt Image Helper for better future features

* Split up the create function into 3 private functions
 * process() which imports the image as a GD resource
 * crop() which crops the GD resource.
 * cache() which saves the resource on the server with a serialized MD5 of the $fileobj changed with the original file (adding the fID if it exists).
* Added an (optionally public) $fileobj variable which contains changes made to the file by setting it's attributes.
* Rebuilt the existing functions to use the new private functions.
* Updated definitions for the PHPdoc.