drop down menu, fix icon link
Merge pull request #46 from leituo56/dev-xiaoli

drop down menu, fix icon link
find_friend function finish
Merge pull request #47 from leituo56/dev-xiaoli

find_friend function finish
edit files for visualization
Merge pull request #48 from leituo56/sammie_visualization

edit files for visualization
update files only
Merge pull request #49 from leituo56/sammie_visualization

update files only