(RM)  Re-read memorized message number

 Re-reads those messages that were previously marked with the (M)ark
 message command.  The RM function can take any of three separate forms:

  RM  = Read the marked message and stop.
  RM+ = Read the marked message then continue going forward.
  RM- = Read the marked message then continue going backward.

 Subcommands
  NONE