constexpr reference like cls.attr.
The tellg does not work as expected in text mode. There is problem with
CRLF on windows. Thus, the file must be opened in binary mode.

MemberReference.

traits apply

way how to detect whether the mesh changed for example for export
purpose.

MeshDataContainer operator=(& and &&) and little documentation

fix of methods setting up the boundary cells

This reverts commit a6c71d46, reversing
changes made to 0a524e29.

Refactor

performance.