sunburst sort attribute

- Standard (original) behavior: sort on values
- new *sort* option to disable sorting

Author: thierryVergult

src/traces/sunburst/calc.js

@@ -192,7 +192,9 @@ exports.calc = function(gd, trace) {
     if(failed) return;
 
     // TODO add way to sort by height also?
-    hierarchy.sort(function(a, b) { return b.value - a.value; });
+    if ( fullLayout[ 'sort']) {
+      hierarchy.sort(function(a, b) { return b.value - a.value; });
+    }
 
     var pullColor;
     var scaleColor;

src/traces/sunburst/layout_attributes.js

@@ -35,5 +35,15 @@ module.exports = {
             'Colors provided in the trace, using `marker.colors`, are never',
             'extended.'
         ].join(' ')
+    },
+    sort: {
+      valType: 'boolean',
+      dflt: true,
+      role: 'style',
+      editType: 'calc',
+      description: [
+          'sort on values.',
+          'default true'
+      ].join(' ')
     }
 };

src/traces/sunburst/layout_defaults.js

@@ -17,4 +17,5 @@ module.exports = function supplyLayoutDefaults(layoutIn, layoutOut) {
     }
     coerce('sunburstcolorway', layoutOut.colorway);
     coerce('extendsunburstcolors');
+    coerce('sort');
 };