Add get position

CHANGELOG.md

 
 - ADDED: Add `setLeftLayers()` and `setRightLayers()` methods
 - ADDED: `options.padding`
+- ADDED: `getPosition()` returns the x coordinate (relative to the map container) of the divider
 - FIXED: **[BREAKING]** Export factory function on `L.control` not `L.Control`
 - FIXED: Slider drag was not working on touch devices
 

index.js

     L.setOptions(this, options)
   },
 
-  getPosition: noop,
+  getPosition: function () {
+    var rangeValue = this._range.value
+    var offset = (0.5 - rangeValue) * (2 * this.options.padding + this.options.thumbSize)
+    return this._map.getSize().x * rangeValue + offset
+  },
 
   setPosition: noop,
 
 
   _updateClip: function () {
     var map = this._map
-    var rangeValue = this._range.value
     var nw = map.containerPointToLayerPoint([0, 0])
     var se = map.containerPointToLayerPoint(map.getSize())
-    var offset = (0.5 - rangeValue) * (2 * this.options.padding + this.options.thumbSize)
-    var clipX = nw.x + (se.x - nw.x) * rangeValue + offset
-    var dividerX = map.getSize().x * rangeValue + offset
+    var clipX = nw.x + this.getPosition()
+    var dividerX = this.getPosition()
 
     this._divider.style.left = dividerX + 'px'
     this.fire('dividermove', {x: dividerX})