MeshLib add properties

This PR is based on the discussion in PR #531:
- It adds an implemention to manage properties within the Mesh.
- The properties are associated to specific mesh items like mesh nodes or mesh
  elements via an enum class (see enum class MeshItemType).
- The properties are not restricted to a particular data type, you can use several types like double, vector or matrix
  types at run time together (see tests).
- There is not a possibility to get the value data type.
@brief Property manager for meshes.
(it's not necessarily only for mat-props and the manager is assigned to mesh, not to items)