implemetend in the package.
A lot of files has been modified because some of the internal syntax has
changed. But the top level methods should still work.

Two tests about the plots of synchronized oscillatory simulations have
been added.

All tests passed.

models. It's a better semantic and improve performance as well as
readability of the code. All the tests passes (except the remark in the
last commit).

Fix about methods of SynchronizedTrajectory + tests.

Simulation for ParametricModel works.