Adds the Enriched Galerkin discretization to HyTeG, contained in directory src/hyteg/egfunctionspace:
- Forms for mass, div, divt, Laplacian and epsilon
- corresponding operators with and without Nitsche-type boundary conditions (Nitsche-operators are preferred due to their symmetry)
- a Stokes-function and operators in directory src/hyteg/composites
- interpolation operators between DG and CG of first degree with P1toDGOperator in directory src/hyteg/dgfunctionspace
- additional addVolumeGhostlayer functionality in vertexDoFFunction required in P1toP0Operator and P0toP1Operator
Two benchmarks with strongy varying viscosity from literature reside in apps/2022-eg-varvisc.
tests/hyteg/egfunctionspace contains tests for operator symmetry, forms, matvec/apply, basic operations of EGFunction and convergence tests.