fixed some performance and cleanup issues

Set this.horizontal and this.vertical properties to null when destroyed
and unbound scroll and mousewheel event listeners tied to the scrollbar
when it is destroyed.

antiscroll.js

@@ -44,7 +44,7 @@
     });
 
     this.refresh();
-  };
+  }
 
   /**
    * refresh scrollbars
@@ -81,9 +81,11 @@
   Antiscroll.prototype.destroy = function () {
     if (this.horizontal) {
       this.horizontal.destroy();
+      this.horizontal = null
     }
     if (this.vertical) {
       this.vertical.destroy();
+      this.vertical = null
     }
     return this;
   };
@@ -126,10 +128,12 @@
     this.el.mousedown($.proxy(this, 'mousedown'));
 
     // scrolling
-    this.pane.inner.scroll($.proxy(this, 'scroll'));
+    this.innerPaneScrollListener = $.proxy(this, 'scroll');
+    this.pane.inner.scroll(this.innerPaneScrollListener);
 
     // wheel -optional-
-    this.pane.inner.bind('mousewheel', $.proxy(this, 'mousewheel'));
+    this.innerPaneMouseWheelListener = $.proxy(this, 'mousewheel');
+    this.pane.inner.bind('mousewheel', this.innerPaneMouseWheelListener);
 
     // show
     var initialDisplay = this.pane.options.initialDisplay;
@@ -138,7 +142,7 @@
       this.show();
       this.hiding = setTimeout($.proxy(this, 'hide'), parseInt(initialDisplay, 10) || 3000);
     }
-  };
+  }
 
   /**
    * Cleans up.
@@ -149,6 +153,8 @@
 
   Scrollbar.prototype.destroy = function () {
     this.el.remove();
+    this.pane.inner.unbind('scroll', this.innerPaneScrollListener);
+    this.pane.inner.unbind('mousewheel', this.innerPaneMouseWheelListener);
     return this;
   };
 
@@ -175,7 +181,7 @@
     if (!this.dragging) {
       this.hide();
     }
-  }
+  };
 
   /**
    * Called upon wrap scroll.
@@ -270,7 +276,7 @@
   Scrollbar.Horizontal = function (pane) {
     this.el = $('<div class="antiscroll-scrollbar antiscroll-scrollbar-horizontal">');
     Scrollbar.call(this, pane);
-  }
+  };
 
   /**
    * Inherits from Scrollbar.
@@ -292,7 +298,7 @@
     this.el
       .css('width', trackWidth * paneWidth / innerEl.scrollWidth)
       .css('left', trackWidth * innerEl.scrollLeft / innerEl.scrollWidth)
-  }
+  };
 
   /**
    * Called upon drag.
@@ -408,7 +414,7 @@
     function f() {};
     f.prototype = ctorB.prototype;
     ctorA.prototype = new f;
-  };
+  }
 
   /**
    * Scrollbar size detection.
@@ -435,6 +441,6 @@
     }
 
     return size;
-  };
+  }
 
 })(jQuery);