Clang format run on near-the-header lines.

Happy New Year

Some boundary conditions might not be applicable to a specific component
but to all components. In this case the optional component id is not
initialized and it is no longer an error.

The main work was done before, but the parser was missing.

When creating a new MeshProperty the number of components was not passed
further.

Adding new mesh properties reqiure non-const access.