Change log

Major changes to existing components

ODEsElements can now return the derivative of the fluxes together with the fluxes. This enables the usage of numerical solvers that use the derivatives (e.g., Newton methods).
Folder structure improved. The numerical approximators and the root finders have been moved from the folder implementation/computation to implementation/numerical_approximators and implementation/root_finders, respectively. Names of the files have been slightly modified to be coherent with this new folder organization.

Implemented a new numerical approximator implementing Runge Kutta 4
Implemented a new root finder implementing a Newton-bisection method
Implemented a new root finder implementing a trivial algorithm to solve explicit algebraic equations.