Image Resizer: Change the size of uploaded image files

This is a simple class that can be used to change the size of images in the GIF, JPEG, and PNG formats.

It may be used to resize uploaded images, so it can also verify whether the image does not exceed a given size, whether it matches expected file name extensions, and that there is no file with the same name in a given pictures directory.

The given image is resized proportionally to a size that does not exceed a given limit width and height.

The resized image file is copied to a given pictures directory.