added 'clear' string to allow the data to purge itself

bin/feedGnuplot

@@ -403,7 +403,10 @@ sub mainThread
     {
       next if /^#/o;
 
-      if($_ !~ /^replot/o)
+      if( $options{stream} && /^clear/o )
+      { clearCurves(); }
+
+      if(! /^replot/o)
       {
         # parse the incoming data lines. The format is
         # x id0 dat0 id1 dat1 ....
@@ -606,6 +609,13 @@ sub setCurveLabel
   updateCurveOptions($curve->[0], $id);
 }
 
+# remove all the curve data
+sub clearCurves
+{
+  foreach my $curve(@curves)
+  { splice( @$curve, 1 ); }
+}
+
 # function to add a point to the plot. Assumes that the curve indexed by $idx already exists
 sub pushPoint
 {