#497118 by chx, catch, pwolanin, JoshuaRogers, and Jacob Singh: Remove the function registry. While the hope was that this would result in improved performance for low-end hosts, it comes at the expense of critical development experience problems and less benefit than something like APC. Class registry remains intact to facilitate autoloading.

Of all the patches to accidentally commit without a message. :( Rolling back registry rip. Let's try that again.

- Patch #373613 by drewish, quicksketch: working around some Debian issues.  They ship a different GD library.

  times (such as crop, scale, then desaturate) without quality loss, we need to
  pass images by their raw GD (or other library) resources rather than re-opening
  the same image repeatedly, which causes wasted processing and loss of quality when
  using JPEG images.  This patch reworks the image toolkits, adds some new image
  manipulations and adds some impressive SimpleTests.

- Patch #270508 by paul.levvik and pwolanin: usability improvement: image toolkits should not have to be copied.

- Patch #245115 by kkaefer, John Morahan, JohnAlbin et al: after a long discussion we've decided to make the concatenation operator consistent with the other operators.

- Patch #148346 by Steef and drewish: split image.inc into image.inc and image.gd.inc and improved the documentation.

- Modified patch #142798 by Steven and sime: introduced a new image API function: image_scale_and_crop()

See: http://drupal.org/node/64279#t-placeholders

  for performance's sake.

- Patch #27863 by Robrecht: fixed order of parameters passed to imagecopy().  Could result in black images.

- Patch #24157 by chx/Robin/...: changed file_exists() to is_file() to fix several problems with modules using theimage toolkit.

- Tweak code style.

- Patch #16358 by James: added toolkit to enable better image handling.  The avatar code and the upload module have been updated to take advantage of the new image API.

There are 5 main functions that modules may now utilize to handle images:

* image_get_info() - this function checks a file.  If it exists and is a valid image file, it will return an array containing things like the pixel dimensions of the image, plus the 'type' and common extension.
* image_scale - resizes a given image to fit within a given width / height dimensions, while maintaining aspect ratio (not distorting the image).  This function can be used to generate thumbnails, or ensure a maximum resolution, etc.
* image_resize - similar to image_scale (but will not respect aspect ratio - may well distort the image).
* image_rotate - rotate an image by X degrees
* image_crop - crops an image to a given rectangle (defined as top-left x/y coordinates plus a width & height of the rectangle).

Contribution modules will now be able to rely on these base manipulation functions to offer additional functionality (such as image nodes, photo galleries, advanced image manipulation, etc).