Replace assertions by custom exceptions

[jorgepiloto]

💻 Feature request: replace assertions by custom exceptions

In most of the solvers, different assertions regarding the validity of the parameters, the convergence to a given accuracy and others are executed. Assertions should only be applied within the tests/ directory. Instead, we must create custom exceptions and raise those, for example: IterationsError, AtolError, RevolutionsError, RtolError, InputError, TransferAngleError.

📝 References

This talks by Mario Corchero titled "Exceptional Exceptions" will be super useful!

1. https://www.youtube.com/watch?v=f3UoZU3hK-c
2. https://www.youtube.com/watch?v=V2fGAv2R5j8

[jorgepiloto]

A color scheme needs to be defined for each one of those errors, so they can be tracked in the IterationsPlotter.