move .h & .m into codes folder.
add basic demo.
update some logic and demo.

delay getting type of attribute til it being transformed.
update the demo codes.
add support for auto mapping.

添加自动映射的支持.在映射开始时尝试根据json的key自动添加开发者未定义的映射规则.

采取from和to相同的方式,如果to在目标类型上没有则不会添加.
add some comments.
Merge branch 'develop'