BC break: classes split into separate files, PHP5 visibility added
Request #2487 : new methods addValidExtension() and hasValidExtension()
Request #19365: add option to allow for multiple extensions on same file
This class provides an advanced file uploader system for file uploads made
from html forms. Features:
* Can handle from one file to multiple files.
* Safe file copying from tmp dir.
* Easy detecting mechanism of valid upload, missing upload or error.
* Gives extensive information about the uploaded file.
* Rename uploaded files in different ways: as it is, safe or unique
* Validate allowed file extensions
* Multiple languages error messages support (es, en, de, fr, it, nl, pt_BR)