Add magres fileformat

A new file format added to the io module - the MAGRES file format is used for ab initio NMR parameters (and related geometries) by CASTEP and Quantum Espresso. A complete example of the file format is provided attached.testfull.magres Further information can be found at http://www.ccpnc.ac.uk/pmwiki.php/CCPNC/Fileformat.

The new parser extracts geometry, lattice, and symmetry, plus places the NMR data in suitable arrays and Atoms.info entries.