Added the grab method
Added the __toString method that prints the image
Made the $width argument mandatory
Modified the PHPDoc, removing the exception
Made the $sourceWidth and $sourceHeight optional
If not specified, $sourceWidth and $sourceHeight are the width and the height of the image to copy
Modified the PHPDoc to reflect the change
Added the insert method
Added the EffectInterface
Now the interface is an interface
Added the EngineInterface
Added the EngineAbstract
Now it extends the EngineInterface
Added the EffectAbstract that extends the EngineAbstract
Now also ManipulateInterface and ManipulateAbstract implements the Engine
Obviously without the inherited methods
__toString method moved into the Engine
Created the Effect class
Added the optional parameters $positionX(Y)
Added the possibility to fill an image also with tiled colors