improve c code readability and fix some warnings
rename and format python files, fix some mistakes
Merge pull request #108 from Boshen/master

improve code/
simple test
crlf
Merge pull request #109 from nagoyanara/master

chapter25.py
add chapter 7 python code
Merge pull request #110 from tdoly/master

add chapter 7 python code
Merge remote-tracking branch 'upstream/master'
sync with upstream