Use const references where necessary.

In PV::createBoundaryConditionsForDeactivatedSubDomains method the boundary
conditions must be created only for the number of components of the specified
variable instead for all components of all variables.

The fmt library happily accepts std::string without
any conversions.

Include spdlog via BaseLib/Logging.h, which
provides macro replacements for
ERR/DBUG/WARN/INFO...

Fixes multiple copyright messages in the doxygen docu.

ag '\\file' -L --ignore=ThirdParty *Lib |xargs  sed -i 's/\(.*\)\\copyright/\1\\file\n\1\\copyright/'

See previous commit for details.

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