add fast sync func (#204)

add fast sync func (#204)

* Modify fast sync function

* Fix GetHeadersMessage error

* Fix skeleton init error

* Fix fetchHeaders error

* Add fetch date finish check

* Fix FetchBodiesTask error

* Fix fetchBodies bug

* Add multi-peer fetch support

* Fix requireHeaders bug

* add lit fast sync func

* Fix fetchBlocks bug

* opz code format

* del test file

* opz code

* Add test case

* change to singe peer fast sync

* Fix bug

* Add peer exception handle

* del unused code

* Add test case

* Fix review bug

* Fix locate headers error

* Fix test file error

* Add irreversible block fast sync

* Fix test err

* Fix review bug