check_constraints and update_state! functions of an Edge in order to
improve performance.
Acutally the gain is low, but it improved the readabilty of the code.
All tests passed.

check_constraint and update_state functions are created inside
create_automaton_*(), by the evaluation of meta_elementary_functions <:
Expr. check_constraint and update_state don't depend on constants::Dict
anymore: constants are interpolated inside the expression.

Add of tests for euclidean distance automaton.
Add a new function euclidean_distance that computes the euclidean
distance of a Trajectory compared to observations along a discrete
timeline.

automata and proba moels are differents. This bug was introduced after
we change the structure of automata in order to better distributed
programming.
It leads to a restructuration of automata. In fine, the structure is
more stable and consistent. It is possible it is more computationally
efficient, but for now it is not well tested.

2) Creation of functions that collects data along with a timeline
over a trajectory + unit test vectorize.

3) Very small fix in plots and abc smc.

Fix about behavior of automata when the initial state is absorbing or
the parameters are equal to zero.

Add of supplementary unit tests.

copyto! is implemented for LHA states.

Automaton G works almost well, a bias in the distance is identified
compared to Cosmos when one of the model parameters is zero.

Implementation of volatile_simulate, which simulates SynchronizedModel
without saving values: it only returns the last LHA state of the
simulation.

Implementation of distributed computations of variable automata with
volatile_simulate.

Tests passed.

Automaton G is implemented and runs OK. Not tested with Cosmos call.

The next step of development is the restruction of data collection for
trajectories.

From now on: Trajectory.values::Matrix{Float64}, it will be
Trajectory.values::Vector{Vector{Float64}}.

According to small performance tests I've made, it will increase the
performance of the package.

Add of a new type of Trajectory: SynchronizedTrajectory which is created
by the simulation of a synchronized model with an LHA.

Simulate function for SynchronizedModel executes and is tested by two
simple models.

Next step : Cosmos based tests.

First implementation of LHA.
Synchronized simulation not yet tested.
Reading of trajectories with LHA seems to work with one test basted on
simulations that checks that the last value is well read.