Update Readme.md
Merge pull request #75 from Boshen/master

improve chapter 7 readability
Update Readme.md
Merge pull request #76 from honeychx/master

title : readme.md changes
Update Readme.md
Update 12~15.0.md

review
Merge pull request #77 from demonyan/patch-1

Update 12~15.0.md
Update Readme.md
Update Readme.md
Update Readme.md
add chapter 38
Update 02.0.md

之前的bit hack有误，0x3f需要改为0x1f。同时考虑到bit version容易误导人，可读性也不强。所以加入了histogram version。
Merge pull request #83 from blackball/patch-1

Update 02.0.md
Merge pull request #82 from badnotes/master

add chapter 38
Update preface.md
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Update Readme.md
improve contents of Readme.md