Re #10462. Added IntegrateFlux algorithm.
Re #10462. More unit tests.
Re #10462. Renamed SXDMDNorm to MDNormSXD.
Re #10462. Unit test for MDNormSXD properties.
Re #10462. Use pre-integrated flux in MDNormSXD.
Re #10462. Documentation. A test case.
Merge branch 'feature/10462_sxdmdnorm_integration' into develop