try prevent segfault in plotting

pub/src/edif.cpp

@@ -1113,11 +1113,12 @@ void NEdif::Plot( CPlot *plot, bool add )
                         printf( "  %u points < ymin\n", nyl );
                     if( nyh )
                         printf( "  %u points > ymax\n", nyh );
+                    continue;
                 } else {
                     plot->plotScan( false, pstyle++,
                                     xp, yp, dyp, *(e->Z(j)),
                                     e->P()->xco.str(), e->P()->yco.str(),
-                                    "data file "+strg(k)+" scan "+strg(j) );
+                                    "data file " + strg(k) + " scan "+strg(j) );
                 }
             } else if ( fc && fc->kconv!=-1 ) {
                 // plot only at x points of convolutand