Improve getting_started docu
Various docu improvements and onset for partitioning howto
First version of the partitioning howto
Use b as key for the Becke scheme
Alphabetically sort scheme keys in horto-Xpart.py sripts
Fix horton-wpart.py script for Becke partitioning
Various cleanups in the periodic table

- Take vdw radii from literature to avoid troubles with Jaguar copyrights.
- Nice columns in data/elements.txt.
- More and complete references.
- Allow None in data/elements.txt.
- Strictly limit Brag-Slater radii to the original values. Other covalent
  radii are present that can be used as backup.
Use old radii in Becke partitioning and new radii in Becke-Lebedev integration grids
Prepare for source distribution package
Update URL for refatoms
Update program description
Update version number to 1.0
Change cartesian moments to cartesian multipoles with proper sign convention
Fix a poor name in espfit code
Website updates
Fix test for source releases