Secure Upload: Process uploaded files of multiple types

This class can process uploaded files of multiple types.

It can check a given submitted file input values and verify if the file name extension is one the allowed for the expected file type. Currently it supports file types of image, audio or document.

For image file types it can check if the file is really an image of the supported types.

If the file size does not exceed the allowed limit or an image file does not exceed the allowed width and height, the class can move the file to the destination upload directory.