Merge pull request #71 from andyque/master

issue #3503. modify event dispatcher article
fixed #3298, modify spell, coding style, wrong grammar. update wrong screenshot.
Merge branch 'master' of https://github.com/cocos2d/cocos-docs
Merge pull request #72 from Ivenyang/master

fixed #3298, modify spell, coding style, wrong grammar. update wrong screenshot.
Merge pull request #21 from cuit-zhaxin/master

	issue #3471 correct the article about Vector
Merge remote-tracking branch 'upstream/master'
issue #3503. modify Vecotr<T> article
issue #3503. modify Vector<T>.
issue #3503. finish the article Vecotr<T>
issue #3503. finish vector article
issue #3503. add some `` to small code snippets.
issue #3503. add subscript operator descripts
issue #3503. modify some typo
issue #3503. remove empty whitespace and add warning section
issue #3503. add namespace to all the classes of cocos2d-x
issue #3503. fix a link display error
issue #3503. remove unused double quote
issue #3503. add best practice to value