Putting computation of forces and moments in a separate class named ContactModel
Changing method for measuring computation time
Revert "Putting computation of forces and moments in a separate class named ContactModel"

This reverts commit af03a235ea7cc8a12eabbd7135bf86ab095ab242.
adding elasting pendulum contact model. We can now choose between two models
correcting a bug in the elast pendulum model and adding the method that permit to choose the contact model in the entity
Modifying elast pendulum contact model and modifying organization of methods that compute and get forces and moments
Changing model for moments and damping of the elast pendulum contact model
merge from stack-of-tasks/state-observation
Deleting useless file at the root and replacing boost_assert by an exception in the computeForcesAndMoments methods
Merge pull request #5 from amifsud/master

Adding double pendulum contact model