Merge branch 'multipie-doc' into 'master'

doc/leaderboard/img/multipie/multipie_E_DET_dev.png

doc/leaderboard/img/multipie/multipie_E_DET_eval.png

doc/leaderboard/img/multipie/multipie_M_DET_dev.png

doc/leaderboard/img/multipie/multipie_M_DET_eval.png

doc/leaderboard/img/multipie/multipie_P_DET_dev.png

doc/leaderboard/img/multipie/multipie_P_DET_eval.png

doc/leaderboard/img/multipie/multipie_U_DET_dev.png

doc/leaderboard/img/multipie/multipie_U_DET_eval.png

doc/leaderboard/img/multipie/multipie_setup.jpg

doc/leaderboard/multipie.rst

doc/leaderboard/script/multipie/pose_analysis.html

doc/leaderboard/script/multipie/pose_analysis.py

doc/leaderboard/table/multipie/multipie_E.csv

doc/leaderboard/table/multipie/multipie_M.csv

doc/leaderboard/table/multipie/multipie_P.csv

doc/leaderboard/table/multipie/multipie_U.csv