Password for public download + 3 patch from evcwally

New function:
Password for public download: you can set up a password for a public download.

Other Patch:
Update upload-import-orphans.php (from evcwally)
Update file-upload.php (from evcwally)
Update core.update.php (from evcwally)

Thanks to
evcwally
Diego Verì (@Snake231088)
fab120