Problem.hpp file

All problem configurations for the scalar transport equations.

This file collects all Problem policy classes for the scalar transport equations, defined in PDE/Transport/Transport.h.

General requirements on Transport 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::SHEAR_DIFF;
}
```
which returns the enum value of the option from the underlying option class, collecting all possible options for coefficients policies.
Must define the function errchk(), doing general error checks.
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 prescribedVelocity(), used to query the prescribed velocity at a point.

Namespaces