%N options %F $MIR/src/subs/options.for
%D Get command line options.
%: user-input
%B
        subroutine Options(key,opts,present,nopt)

        implicit none
        character key*(*)
        integer nopt
        character opts(nopt)*(*)
        logical present(nopt)

  Get options from the command line, and return to the caller those
  options that are present. For example, assume the task keyword is
  "options", and that possible options are, say, display,movie,fiddle, etc
  then this examines the command line:
    task options=fiddle
  and returns indicating that "fiddle" was present, but "display" and
  "movie" were absent.
  This will allow the user to abbreviate options to uniqueness, and will
  generate an error if there is an ambiguous option.

  Inputs:
    key        The task keyword to use.
    opts       An array of possible option values. These should be in lower
               case.
    nopt       The number of possible options.
  Output:
    present    This indicates whether the option was present.
