Whitespace cleanup for extend Collection.prototype.chain function definitions.
Merge pull request #1264 from gsamokovarov/patch-1

Whitespace cleanup for extend and Collection.prototype.chain
updating linkedin example app
Merge branch 'master' of github.com:documentcloud/backbone
null and undefined are invalid ids.
Update QUnit.

* Use `deepEqual` in place of `same`.
* Expect 0 tests where appropriate.
* Update view test to use #qunit-fixture.
* Remove `QUnit.config.reorder = false;`.
Merge pull request #1274 from braddunbar/null-id

null and undefined are invalid ids.
Merge pull request #1275 from braddunbar/qunit-1.5.0

Update QUnit.
Fix #1282 - "all" callback list is retrieved for each event.
Merge pull request #1283 from braddunbar/retrieve-all

Fix #1282 - "all" callback list is retrieved for each event.
refactor events using array instead of linked-list to improve performance
Avoid throwing when $ is not defined.
Merge pull request #1284 from lifesinger/master

Improve performance using array instead of linked-list to implement Backbone.Events
Tweak events implementation.
Merge pull request #1285 from braddunbar/ajax

Avoid throwing when $ is not defined.
Fix #1292 - unexpected results when passing undefined to Model.hasChanged()

* additional check in hashChanged for when `attr` is present but undefined
* adds tests for expected results when passing undefined
simplifying hasChanged if statement
updating model.previous arguments check to match hasChanged
Refactor _prepareModel.
Merge pull request #1295 from braddunbar/refactor-preparemodel

Refactor _prepareModel.