This avoids unnecessary copy initialization
and value parameters.

This is automatic replacement with
ag '(?<!std::)size_t(?!\w)' --ignore-dir=ThirdParty -l | xargs perl -pi.bak -e  's/(?<!std::)size_t(?!\w)/std::size_t/g'

The rewrite gives factor 3 speedup.

moved Mesh::removeUnusedMeshNodes() to new MeshQualityController class and removed duplicate code from removeMeshNodes command line tool