vlt.file.createpath

  CREATEPATH - create a directory path to a given file name, if necessary

  [B,ERRORMSG] = CREATEPATH(FILENAME)

  This function creates all directories that are necessary to
  store the file FILENAME, if they don't already exist. If
  the directories already exist, no action is taken.

  If the function succeeds, B is 1 and ERRORMSG is empty.
  Otherwise, B is 0 and ERRORMSG contains the error.