Saves few deep copies in the current implementation of
the deactivated subdomains and can be further used
to eliminate the unique_ptr return type pattern
occuring in the construction of final or intermediate
objects.

Explicitly delete Mesh assignments:
Because the mesh id is unique (const member set from global
counter) the assignments should be forbidden (explicitly)
because comparison of meshes by ids would be broken.

In:
 - createMeshFromElementSelection: creation of bulk node ids
 - createMeshFromElementSelection: iteration over a map of nodes
 - findElementsConnectedToNodes: iteration over element's nodes
 - Mesh copy constructor: iteration over cloned elements

The elements of the range must support the getID() function.

For the nodes the function is trivial in most cases because the
numbering of the nodes is guaranteed to be 0, 1, ..., n-1 for n nodes
upon mesh creation.

But for an arbitrary set of nodes the numbering might be different.

i.e. replaced getElementSizes with
getMaxiumElementEdgeLengths

Extract allNodesUsed(), existCollapsibleNodes(), and evaluateElementGeometry()
from MeshValidation constructor that can be removed afterwards.

Fixes issues in code quality report.

Rename Point3d::getCoords() -> Point3d::data() and WeightedPoint::getCoords() -> WeightedPoint::data().