Function: Resets the mbstring internal encoding to a users previously set encoding.

Function: Filters/validates a variable as a boolean.

Function: Deletes a file.

Function: Tests if the supplied date is valid for the Gregorian calendar.

Function: Loads the auth check for monitoring whether the user is still logged in.

Function: Outputs the HTML that shows the wp-login dialog when the user is no longer logged in.

Function: Tests if the current device has the capability to upload files.

Function: Tests if a given path is a stream URL