* libblock/src/diskdevs.c: Create the devices as block devices.
* libmisc/shell/main_debugrfs.c, libmisc/shell/main_mkrfs.c,
libmisc/shell/main_mount_rfs.c: New.
* libmisc/shell/main_msdosfmt.c: Change the command to mkdos and
alias the old name.
* libmisc/shell/shellconfig.h, libmisc/Makefile.am: Add RFS
support.
* libfs/src/rfs/rtems-rfs-shell.c,
libfs/src/rfs/rtems-rfs-shell.h: Move the format command code into
the shell file.
