git move next /prev

    1.clone a github repo
    2.create a localbranch 'dev' in first commit

    3.use <git merge commitid> to move next
        git merge 46d861a

    4.use <git reset commitid> to move prev
        git reset a765d751

    5.after use git reset,some file maybe new add,or modify

        1.new add use git clean use clean them

        git clean -dfx (d:directory,f:force,x:not just .ignore file)

        2.modify use git checkout filename to reset them            
        git checkout README.md