Supporting Files uploaded as an array

PHP allows you to set the name attribute on the input field in such a way that multiple files are uploaded as an array. Transliteration doesn't take this possibility into account and runs into errors as it tries to pass arrays to preg_match() and strtolower()

This patch (built against 6.x-3.x, but successfully applied to 7.x-3.x) modifies transliteration_clean_filename() to behave recursively if $filename happens to be an array.

For an example of a module that uses this functionality, see the Webform Multifile sandbox module.