Merge remote-tracking branch 'remotes/origin/master'

Conflicts:
	.gitignore

Signed-off-by: velicue <chenming.eecs@pku.edu.cn>
Merge remote-tracking branch 'remotes/origin/master'

Conflicts:
	.gitignore

Signed-off-by: velicue <chenming.eecs@pku.edu.cn>