The directory name must not contain wildcards (standard convention).
However if a RAM device is not specified, it will automatically be included
(the current) into the directory name.

The buffer of the directory name must have space enough to get itself expanded
with a device name (additional 6 bytes).

IN:     BHL = pointer to null-terminated directory path name

out, if successful:
        Fc = 0, directory successfully created

out, if failed:
        Fc = 1, unable to create directory
        A = error code:
             RC_IVF, Invalid directory path name
             RC_USE, Directory in use
             RC_EXIS, Directory already exists

   registers changed after return:
        A.BCDEHL/IXIY  same
        .F....../....  differentIN: