For proper lookup of the boundary mesh via bulk node ids mapping.

Both functions for reuse.

Will consider to rewrite partitionLookup as a functor.

Add numberOfRegularNodes().

The move ctor is not implemented in gcc < 5.

Remove code duplication and use applyPropertyVector.

This allows to unify the processNodeProperties() and
the processCellProperties().

Extract specific (to node or cell) functions, generalize
some of the loops.

There are still some code duplications, but more difficult
to extract...

Split "config_data" into partition data and offsets.

Also extract a code enumerating the partition's local
nodes.

It's not accessing any members of the class.

Extract both the original function from the class and
a function for a partition.

This required an access function to the partion ids
and the mesh.

Clang format run on near-the-header lines.

Happy New Year

Fix warning: unused parameter ‘is_mixed_high_order_linear_elems’