add Vitor's exercises and data
add first kinematics exercise
offset acceleration by 1 timestep
more kinematics stuff

--HG--
rename : kinimatics/1-walking.ipynb => kinematics/1-walking.ipynb
rename : kinimatics/CESPA Summer Course - Exercises.pdf => kinematics/CESPA Summer Course - Exercises.pdf
rename : kinimatics/walk0001.txt => kinematics/walk0001.txt