Refractor Shallow Water Equation solver to reduce duplication

Issue/feature addressed

ShallowWaterSystem has been refactored to reduce duplication. The motivation is to tidy-up the ShallowWaterSystem classes to implement time-implicit discretization for the Parareal work.

The following functions have been moved to the ShallowWaterSystem base class:

• DoOdeProjection
• SetBoundaryConditions
• WallBoundary2D
• WallBoundary
• AddCoriolis

In addition:

• Use default keyword for destructor
• Clean-up implementation of ConservativeToPrimitive and PrimitiveToConservative and remove unnecessary virtual functions
• Remove unused function declaration NumericalFlux1D and NumericalFlux2D
• Remove using namespace std;
• The NonlinearPeregrine has been refractored as a subclass of NonlinearSWE

Proposed solution

Implementation

Tests

Suggested reviewers

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Notes

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Checklist

• Functions and classes, or changes to them, are documented.
• [ ] User guide/documentation is updated.
• Changelog is updated.
• [ ] Suitable tests added for new functionality.
• Contributed code is correctly formatted. (See the contributing guidelines).
• [ ] License added to any new files.
• No extraneous files have been added (e.g. compiler output or test data files).