SYNOPSIS
        string read_file(string file, int start, int number)

DESCRIPTION
        Reads lines from file.
        If <start> is not given or 0, the file is read from the
        beginning, else the efun skips the given number of lines and
        starts reading from the next one.

        If <number> is not given or 0, the whole file is read, else
        just the given amount of lines.

        If <start> would be outside the actual size of the file, 0 is
        returned instead of a string.

SEE ALSO
        read_bytes(E), write_file(E)