I now always 'exit -1' on error

bin/feedgnuplot

@@ -173,7 +173,7 @@ sub interpretCommandline
       else
       {
         print STDERR "--stream can only take in values >=0 or 'trigger'\n";
-        exit 1;
+        exit -1;
       }
     }
 
@@ -184,7 +184,7 @@ sub interpretCommandline
     elsif ( $options->{stream} <= 0)
     {
       print STDERR "--stream can only take in values >=0 or 'trigger'\n";
-      exit 1;
+      exit -1;
     }
   }
 
@@ -655,7 +655,7 @@ sub getCurve
   {
     print STDERR "Tried to exceed the --maxcurves setting.\n";
     print STDERR "Invoke with a higher --maxcurves limit if you really want to do this.\n";
-    exit;
+    exit -1;
   }
 
   my ($id) = @_;