2.0.0

Dependencies dictionary added:

1. Improving caching strategy
2. Improving initialization of Stateful objects
3. Other possible future applications (graph generation...)

Manage model components:

1. Components class to load model and manage them, allowing inline changes
2. Control variables managing through Time class, allowing dynamic final_time, time_step and saveper.

Several bug fixes (modulo, exponentials)

General cleanup

Improvements in the documentation