Parrallel computations

[VEZY]

Add parallel computations over objects, time-steps and models.

• Use Threads.@threads, see : c7b7c6c
• Use Floops.@floops instead to manage Sequential, Multi-threaded or Distributed computations with an executor argument. See 3d91bb0
• Add a trait on models to tell if they are independent between objects and or time-steps. Then only the ones that are independent can be run in parallel. We have to add a test on that in src/run.jl to put the executor to Sequential if needed, see: 88abf14
• Look into locks for parallel computations over "independent" processes that can maybe call a model when both parents are being computed, so both are set to 0 and the model is never called

[Samuel-amap]

Closing this issue, it is somewhat outdated when compared to current concerns and the potential directions that can be taken in terms of parallelization.