std::vector<std::size_t> _ids_of_active_elements.

due to its std::unique_ptr type instance.

Use the specified patch mesh instead of the entire bulk mesh to define
the source term.

Used in construction of mesh names in two places.
This unifies the name.

Removing most of the code duplication in the BCs/STs creation.

Find a boundary mesh in the list of meshes instead of using GeoObjects
and pass it to the boundary condition creation.

Clang format run on near-the-header lines.

Happy New Year

Some boundary conditions might not be applicable to a specific component
but to all components. In this case the optional component id is not
initialized and it is no longer an error.