Code Refactoring

[dalixwill]

@katiana22

calibration.py is a beast of a document. Let's figure out how to make it a bit easier to digest.

There are the following classes:

1. OptimizationModel
2. Parameter
3. Parameters
4. Reference
5. Observation

and free-standing functions:

1. ego
2. plotComparison
3. plotConvergence
4. compareMatrices
5. getContinuumFieldValues
6. plotFields
7. getContinuumFieldValues
8. computeContinuumDeviatoricStress
9. main

We could start by moving all code related to plots to a separate.py file. After that, I dunno