[all] Unifying how topological change are handled in mappings.

[damienmarchal]

In PR #217

#ifdef BARYCENTRIC_MAPPER_TOPOCHANGE_REINIT
    // handle topology changes in the From topology
    virtual void handleTopologyChange(core::topology::Topology* t);
#endif // BARYCENTRIC_MAPPER_TOPOCHANGE_REINIT

Is coding to change to runtime condition instead of #IFDEF.

@JeremieA pointed that this rise consistency issues in how the topology changes are handled into the mapping.

Maybe we should keep that in mind and in some future do something (eg making a test that should be done all mapping to validate a consistent and clear behavior).