Description:
------------
There is a function array_change_key_case but not array_change_value_case. This should be part of the language.

Something like this:
/**
 * @brief Returns an array with all values lowercased or uppercased.
 * @return array Returns an array with all values lowercased or uppercased.
 * @param object $input The array to work on 
 * @param int $case [optional] Either \c CASE_UPPER or \c CASE_LOWER (default).
 */
function array_change_value_case(array $input, $case = CASE_LOWER) {
	switch ($case) {
		case CASE_LOWER:
			return array_map('strtolower', $input);
			break;
		case CASE_UPPER:
			return array_map('strtoupper', $input);
			break;
		default:
			trigger_error('Case is not valid, CASE_LOWER or CASE_UPPER only', E_USER_ERROR);
			return false;
	}
}