Update file.php

Prevents security issue where $file can be an empty string or directory path. If that happens the deletion fails but the directory is left writeable with 0777 permissions. If $file is empty then this is interpreted by chmod as the current director, so root folder of Joomla site is left writeable.
Update file.php
Update file.php
Align docblock of JVersion

Light modification of docblock.
Merge pull request #3495 from asika32764/patch-2

Align docblock of JVersion
[#3289] Wrong message for empty contact category list (Fix #3290)
Merge pull request #3448 from fcoulter/staging

Update file.php