feat: finalize.callback called with result

As `finalize` is called with `triggerHandler` we can read back the result from the handlers and forward to the `finalize` callback. This means we can now do this:

```javascript
var Widget = require("mu-jquery-widget/widget");
var W = Widget.extend({
  "on/finalize": function ($event, finalized) {
    finalized(function(result) {
      console.log(result === "result" // true
    });
    return "result";
  }
 });

var w = new W($("<div>", "ns");
w.remove();
```

BREAKING CHANGE: The removal of event handlers in `finalize` is removed in this commit as it's just as easy to do `w.off()` on your own when needed.

tests/widget.js

@@ -40,54 +40,31 @@
     assert.deepEqual(C.concat(), Widget.concat(a, b));
   });
 
-  QUnit.test("finalize removes handlers sync", function (assert) {
+  QUnit.test("finalize triggered on .remove()", function (assert) {
     assert.expect(1);
 
-    var count = 0;
     var $element = $("<div></div>");
     var W = Widget.extend({
-      "on/test": function () {
-        assert.ok(count++ === 0, "handler called " + count + " times");
+      "on/finalize": function () {
+        assert.ok(true, "handler called");
       }
     });
     var w = new W($element, "ns");
 
-    $element
-      .trigger("test")
-      .trigger("finalize.ns")
-      .trigger("test");
+    $element.remove();
   });
 
-  QUnit.test("finalize removes handlers async", function (assert) {
+  QUnit.test("finalize called with $.Callbacks", function (assert) {
     assert.expect(2);
 
-    var count = 0;
-    var $element = $("<div></div>");
-    var W = Widget.extend({
-      "on/test": function () {
-        assert.ok(count++ <= 1, "handler called " + count + " times");
-      }
-    });
-    var w = new W($element, "ns");
-    var c = $.Callbacks("once");
-
-    $element
-      .trigger("test")
-      .trigger("finalize.ns", c.add)
-      .trigger("test");
-
-    c.fire();
-
-    $element.trigger("test");
-  });
-
-  QUnit.test("finalize triggered on .remove()", function (assert) {
-    assert.expect(1);
-
     var $element = $("<div></div>");
     var W = Widget.extend({
-      "on/finalize": function () {
-        assert.ok(true, "handler called");
+      "on/finalize": function ($event, finalized) {
+        finalized(function(result) {
+          assert.ok(true, "handler called");
+          assert.equal("result", result, "result matches");
+        });
+        return "result";
       }
     });
     var w = new W($element, "ns");

widget.js

@@ -33,19 +33,7 @@
       var me = this;
       var $element = me.$element;
       var finalized = $element.constructor.Callbacks("once");
-      $element.triggerHandler("finalize." + me.ns, finalized.add);
-      finalized.fire();
-    },
-    "on/finalize": function ($event, cb) {
-      var me = this;
-      if (cb) {
-        cb(function () {
-          me.off();
-        });
-      }
-      else {
-        me.off();
-      }
+      finalized.fire($element.triggerHandler("finalize." + me.ns, finalized.add));
     }
   };