fix(bpmnpaletteprovider): workaround for incorrect layouting of connections

The layout algorithm is broken for decimal coordinates see #143
This is a workaround to not trigger the bug when using the palette.

lib/features/palette/BpmnPaletteProvider.js

@@ -33,8 +33,8 @@ BpmnPaletteProvider.prototype.getPaletteEntries = function(element) {
   var vbox = canvas.viewbox();
 
   var center = {
-    x: vbox.outer.width  * 1 / vbox.scale / 2,
+    x: Math.round(vbox.outer.width  * 1 / vbox.scale / 2),
-    y: vbox.outer.height * 1 / vbox.scale / 2
+    y: Math.round(vbox.outer.height * 1 / vbox.scale / 2)
   };
 
   _.extend(actions, {