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

There is another one, which is used.

Eliminate two single-line functions.

The flat vector of staggered solution simplifies the data access.

Fixing the location of phasefield/temperature/displacement
subvectors in phase field processes.

Some of the staggered processes use previous solution
to compute time derivative of the solution.

The test also tests the openflowboundary for the non advective implementation of hc process

--amend

Fixes multiple copyright messages in the doxygen docu.

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

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.

Including
 - usage of static_cast instead of c-style cast,
 - single variable declaration per line,
 - removing const from return types
 - omit unnecessary string to char* conversions,

The used clang-tidy checks are:
google-readability-casting,
readability-const-return-type,
readability-container-size-empty,
readability-delete-null-pointer,
readability-deleted-default,
readability-else-after-return,
readability-function-size,
readability-identifier-naming,
readability-inconsistent-declaration-parameter-name,
readability-isolate-declaration,
readability-misleading-indentation,
readability-misplaced-array-index,
readability-named-parameter,
readability-redundant-*,
readability-simplify-*,
readability-static-accessed-through-instance,
readability-static-definition-in-anonymous-namespace,
readability-string-compare,
readability-uniqueptr-delete-release

Either by renaming or removing the variable or adding
an extra scope to the top variable.

CPPCheck warning type: shadowVar.

See previous commit for details.