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.
i would remove a default type for mesh item type, because there is no typical case (we use both node and cell values). with the default value, one can write like `getProperty(name)` or `addProperty(name)` which doesn't tell you clearly to which mesh item types the property is assigned.