GIF Creator: Create animations in GIF format from an image list

This class can be used to create animations in GIF format from an image list.

It is based on the GIF images into animated GIF with native PHP class originally written by László Zsidi.

This version can compose animations using images of different formats that are converted to GIF and resized to the animation size before assembling the animation if necessary.

It also supports having custom horizontal and vertical offsets, transparency and disposal settings on a per-frame basis.