Problem.hpp file

All problem configurations for the compressible flow equations.

This file collects all Problem policy classes for the compressible flow equations, defined in PDE/MultiMat/MultiMat.h.

General requirements on MuliMatCompFlow Problem policy classes:

Must define the static function type(), returning the enum value of the policy option. Example:
```
static ctr::ProblemType type() noexcept {
  return ctr::ProblemType::USER_DEFINED;
}
```
which returns the enum value of the option from the underlying option class, collecting all possible options for problem policies.
Must define the static function names(), returning the names of integral variables to be output to diagnostics file.
Must define the static function initialize(), used for initialization of the computed fields at time t.
Must define the static function analyticSolution(), used for sampling the analytical solution if exist) at time t.
Must define the static function src(), used for adding source terms to the righ hand side.
Must define the static function dirbc(), used to query Dirichlet boundary condition value on a given side set for all components in the PDE system.

Namespaces