Errors correction and translation of the notebook

Errors fixed:
 - issues with dt, duration and time vector
 - dependancy issues
 - minor issues (typos, etc.)

Errors unfixed:
 - dmp do not work, step functions do.

Changes:
 - creation of default config
 - new function that returns cartesian coordinates.

Notes :
In default config, m is a 10-length array.

Translation of the animation notebook