Main reason for modification is the getFlux function, which for
particular processes (ComponentTransport) relies on all solutions being
available.
This modification ripples through all of the code, especially through
the boundary conditions.
Modified `applyNaturalBC`, `preTimestep`, `integrate`, and `assemble`
functions.

Passing a vector of solutions now.

preTimestep now accepts a vector of solution together with
a process_id.
In postTimestep only the vector of solutions has been changed.

Eliminate two single-line functions.

Fixes multiple copyright messages in the doxygen docu.

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

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

for flexibility in coupling.

 VectorMatrixAssemble::assembleWithJacobian

Clang format run on near-the-header lines.

Happy New Year

 in creating of the instances of classes of coupled processes.

 from the two classes of coupled term.

[Coupling] Changed the members of the coupled term,

 which only contains the solutions of the coupled equations.