rangeslider: keep ref of input rangeslider container

- so that computed rangeslider range can be copied
  into input container, ensuring that the autorange routine
  isn't called on updates.

Author: etpinard

src/components/rangeslider/defaults.js

@@ -15,8 +15,12 @@ var attributes = require('./attributes');
 module.exports = function handleDefaults(layoutIn, layoutOut, axName, counterAxes) {
     if(!layoutIn[axName].rangeslider) return;
 
-    var containerIn = Lib.isPlainObject(layoutIn[axName].rangeslider) ?
-            layoutIn[axName].rangeslider : {},
+    // not super proud of this (maybe store _ in axis object instead
+    if(!Lib.isPlainObject(layoutIn[axName].rangeslider)) {
+        layoutIn[axName].rangeslider = {};
+    }
+
+    var containerIn = layoutIn[axName].rangeslider,
         containerOut = layoutOut[axName].rangeslider = {};
 
     function coerce(attr, dflt) {
@@ -48,4 +52,7 @@ module.exports = function handleDefaults(layoutIn, layoutOut, axName, counterAxe
             layoutOut[ax] = opposing;
         });
     }
+
+    // to map back range slider (auto) range
+    containerOut._input = containerIn;
 };