fixes not concerning graphics

- default is no graphics
- use send_file instead of response (proper mimetype)
- fix issues with parameter blocks

client/jsFiles/SEAWebClientGraphics.js

@@ -798,6 +798,7 @@ let graphs = (function (){
     }
 
     function resizeHandler() {
+      if (blocks) { // prevent error when graphics are not used
         createGraphs();
         adjustLegends();
         if (cursorLinePos) {
@@ -805,6 +806,7 @@ let graphs = (function (){
             cursorLine(null);
             update();
         }
+      }
     }
     window.addEventListener('resize', resizeHandler);
 
@@ -1463,4 +1465,4 @@ function updateCharts2(graph){
 
 function createCharts2(arg) {
     console.log('C2', arg)
-}
+}