Return a list of names of files in DIRECTORY.
There are three optional arguments:
If FULL is non-nil, return absolute file names. Otherwise return names
that are relative to the specified directory.
If MATCH is non-nil, mention only file names that match the regexp MATCH.
If NOSORT is non-nil, the list is not sorted--its order is unpredictable.
Otherwise, the list returned is sorted with `string-lessp'.
NOSORT is useful if you plan to sort the result yourself.
(fn DIRECTORY &optional FULL MATCH NOSORT)