Retrieve IDs that are not already present in the cache.

From php.net (modified by Mark Jaquith to behave like the native PHP5 function).

Kills WordPress execution and displays JSON response with an error message.

Kills WordPress execution and displays JSONP response with an error message.

Set the localized direction for MCE plugin.

Kills WordPress execution and displays an error message.

Accesses an array in depth based on a path of keys.

Sets an array in depth based on a path of keys.

Helper function to test if each of an array of file names could conflict with existing files.

Helper function to check if a file name could match an existing image sub-size file name.