lab1 framework
the first commit, modified pointer *s
modified main.c to add some test cases
fixed bugs of test cases.
created stdarg.h to write a v-a func
modified stdarg.h
finished the basic lines of vfprintf.c
finished lab1.part1 :-p
finished :-)
added a readme
Merge branch 'master' of https://github.com/appcell/OSLab1