* provide interfaces for cell-><lattice> & lattice-><crystal>
* test test test
* document

* cmlAddTable

* Check allowed attributes for parameter (and all other elements) - done
* Tidy up m_wcml_core - done
* Do m4 correctly for stml - done
* redo m4 build for quantity -done
* m4 for all start/end lists - done
* m4 for metadata - done
* move eigenvalues to m_wcml_coma, and allow for assumed-shape arrays - done
* move Crystal to m_wcml_lattice - done
* explicitly list all public interfaces - done
* find units namespace - done
* share definition of sp/dp - done
