Fix a bug in event dispatch.

If an event listener is removed during an event dispatch, it shouldn't receive
the active event. So now in addition to storing a defensive copy, we use a
wrapper object for the event handler to store an `on` boolean. This is set to
false when the listener is removed, preventing that handler from receiving the current event.

src/Dispatch.js

@@ -1,32 +1,35 @@
 po.dispatch = function(that) {
-  var handlers = {};
+  var types = {};
 
   that.on = function(type, handler) {
-    var array = handlers[type] || (handlers[type] = []);
-    for (var i = 0; i < array.length; i++) {
-      if (array[i] == handler) return that; // already registered
+    var listeners = types[type] || (types[type] = []);
+    for (var i = 0; i < listeners.length; i++) {
+      if (listeners[i].handler == handler) return that; // already registered
     }
-    array.push(handler);
+    listeners.push({handler: handler, on: true});
     return that;
   };
 
   that.off = function(type, handler) {
-    var array = handlers[type];
-    if (array) for (var i = 0; i < array.length; i++) {
-      if (array[i] == handler) {
-        array.splice(i, 1);
+    var listeners = types[type];
+    if (listeners) for (var i = 0; i < listeners.length; i++) {
+      var l = listeners[i];
+      if (l.handler == handler) {
+        l.on = false;
+        listeners.splice(i, 1);
         break;
       }
     }
     return that;
   };
 
   return function(event) {
-    var array = handlers[event.type];
-    if (!array) return;
-    array = array.slice(); // defensive copy
-    for (var i = 0; i < array.length; i++) {
-      array[i].call(that, event);
+    var listeners = types[event.type];
+    if (!listeners) return;
+    listeners = listeners.slice(); // defensive copy
+    for (var i = 0; i < listeners.length; i++) {
+      var l = listeners[i];
+      if (l.on) l.handler.call(that, event);
     }
   };
 };

src/start.js

@@ -2,4 +2,4 @@ if (!org) var org = {};
 if (!org.polymaps) org.polymaps = {};
 (function(po){
 
-  po.version = "1.0.7"; // semver.org
+  po.version = "1.0.8"; // semver.org