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.

Julia shouldn't crash but rather raise an error about the existence
of a function generated by metaprogramming. I didn't manage to isolate
the segfault withtout the package.
To overcome the issue, I add another level of multiple dispatch/abstract
type for synchronized models.
Test of the euclidean distance automaton works.

Meta code generation for next_state! and simulation of synchronized trajectories. bench/pkg/euclidean_distance*.jl works but segfault with test/automata/euclidean*

This commit groups the change operated to the creation of models and
simulate function of a ContinuousTimeModel.
The general idea is to create a concrete type and a simulate function
 per model creation by metaprogramming.
- Now, ContinuousTimeModel is an abstract type. Each creation of a model
defines a concrete type T <: ContinuousTimeModel by meta programming.
- f! and isabsorbing ContinuousTimeModel fields are Symbols.
- simulate(::ContinuousTimeModel) is run by multiple dispatch, according
to the type of the model.

Can't run the whole tests for now but unit/simulate_available_models.jl
runs properly (i've updated the list of models in this commit), and I've
manually checked in the repl that simulations run correctly (distributed
/ plots).

edge_candidates on top-level of next_state! function.

allocation per next_state!. Now update_state! functions returns a Symbol
as location instead of modifying a vector.

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.

integrated poisson model wasn't updated
improvement of plots
fix of synchronized simulation when state is absorbing
All tests passed

All automata were readapted and are in accordance with the last description of the thesis. Tests passed