v0.1.3

Changed how the ODE/DDE adjoint are implemented by leveraging augmented ODE/DDE systems. This is mentioned in the Neural ODE paper, for DDEs this is less evident. (#46)

Refactored Runge Kutta solver in a mother class (#45).

Breaking changes :

• ODE/ DDE vector fields args now becomes func_args.
• Remove has_aux argument from solver's step method.