The structure is small and does not require to be stored on heap.

The evaluation of solid density is moved to the
updateConstitutiveRelations.

Exemplary on SmallDeformationProcess, storage of dt
is no longer required and the assembly can be repeated
without dependency on the t/dt values.

With this it becomes possible to use the t/dt values
directly instead of storing them in *ProcessData
and retrieving at later point.

Fixes multiple copyright messages in the doxygen docu.

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

This reverts commit d825ea54.

Also add default initialization where needed.

The defaulted constructors and assignments will be
generated by default anyway. The deleted ctors and
assignments do not change the class behaviour at all
and by the compiler generated default versions are
good enough too.

Clang format run on near-the-header lines.

Happy New Year

Store the results in the process data.