Return logical status variable from file functions for Matlab compatibility. * NEWS: Announce change. * dirfns.cc (Frmdir): Update documentation. Change return status to true/false rather than 1.0/0.0. * copyfile.m: Update documentation. Change internal variable "sts" to logical variable. Change any assignments to status to true/false. * movefile.m: Update documentation. Change internal variable "sts" to logical variable. Change any assignments to status to true/false. * mkdir.m: Update documentation. * mkdir.m (mkdir_recur): Change internal variable "status" to logical.