#1920 Making flocharts adhere to the curve configuration also changing the default configuration for grpah and flowchart

src/dagre-wrapper/edges.js

@@ -350,6 +350,15 @@ export const insertEdge = function(elem, e, edge, clusterDb, diagramType, graph)
   const lineData = points.filter(p => !Number.isNaN(p.y));
 
   // This is the accessor function we talked about above
+  let curve;
+  // Currently only flowcharts get the curve from the settings, perhaps this should
+  // be expanded to a common setting? Restricting it for now in order not to cause side-effects that
+  // have not been thought through
+  if (diagramType === 'graph' || diagramType === 'flowchart') {
+    curve = edge.curve || curveBasis;
+  } else {
+    curve = curveBasis;
+  }
   const lineFunction = line()
     .x(function(d) {
       return d.x;
@@ -357,7 +366,7 @@ export const insertEdge = function(elem, e, edge, clusterDb, diagramType, graph)
     .y(function(d) {
       return d.y;
     })
-    .curve(curveBasis);
+    .curve(curve);
 
   // Contruct stroke classes based on properties
   let strokeClasses;

src/defaultConfig.js

@@ -184,9 +184,9 @@ const config = {
      *| curve | Defines how mermaid renders curves for flowcharts. | String | Required | Basis, Linear, Cardinal|
      *
      ***Notes:
-     *Default Vaue: Linear**
+     *Default Vaue: monotoneX**
      */
-    curve: 'linear',
+    curve: 'monotoneX',
     // Only used in new experimental rendering
     // represents the padding between the labels and the shape
     padding: 15,

src/diagrams/flowchart/flowRenderer.js

@@ -1,5 +1,5 @@
 import graphlib from 'graphlib';
-import { select, curveLinear, selectAll } from 'd3';
+import { select, curveLinear, curveNatural, selectAll } from 'd3';
 
 import flowDb from './flowDb';
 import flow from './parser/flow';