The `set` command sets _lots_ of options.  No screen is drawn, however, until
 a `plot`, `splot`, or `replot` command is given.

 The `show` command shows their settings.  `show all` shows all the
 settings.

Subtopics available for set:
      angles         arrow          autoscale      bar
      bmargin        border         boxwidth       clabel
      clip           cntrparam      contour        data
      dgrid3d        dummy          encoding       format
      function       grid           hidden3d       isosamples
      key            label          linestyle      lmargin
      locale         logscale       mapping        margin
      missing        multiplot      mx2tics        mxtics
      my2tics        mytics         mztics         noarrow
      noautoscale    noborder       noclabel       noclip
      nocontour      nodgrid3d      nogrid         nohidden3d
      nokey          nolabel        nolinestyle    nologscale
      nomultiplot    nomx2tics      nomxtics       nomy2tics
      nomytics       nomztics       nooffsets      noparametric
      nopolar        nosurface      notime         nox2dtics
      nox2mtics      nox2tics       nox2zeroaxis   noxdtics
      noxmtics       noxtics        noxzeroaxis    noy2dtics
      noy2mtics      noy2tics       noy2zeroaxis   noydtics
      noymtics       noytics        noyzeroaxis    nozdtics
      nozeroaxis     nozmtics       noztics        offsets
      origin         output         parametric     pointsize
      polar          rmargin        rrange         samples
      size           style          surface        term
      terminal       tics           ticscale       ticslevel
      time           timefmt        title          tmargin
      trange         urange         view           vrange
      x2data         x2dtics        x2label        x2mtics
      x2range        x2tics         x2zeroaxis     xdata
      xdtics         xlabel         xmtics         xrange
      xtics          xzeroaxis      y2data         y2dtics
      y2label        y2mtics        y2range        y2tics
      y2zeroaxis     ydata          ydtics         ylabel
      ymtics         yrange         ytics          yzeroaxis
      zdata          zdtics         zero           zeroaxis
      zlabel         zmtics         zrange         ztics