Mendeleev

-------------------

* Updated the electron affinity of Pb and Co.
* Updates of the docs.

-------------------

* Maintenance.

-------------------

* Mainly maintenance updates to docs, sphinx ``conf.py``, ``setup.py``, requirements.

-------------------

Features added
^^^^^^^^^^^^^^

* Added calculation of Martynov and Batsanov scale of electronegativity in
``en_martynov_batsanov`` method in the ``Element`` class
* Added ``abundance_crust`` and ``abundance_sea`` with element abundancies in
the crust and seas
* Added ``molcas_gv_color`` attribute with `MOLCAS GV <http://www.molcas.org/GV/>`_
colors

Bugs fixed
^^^^^^^^^^

* Restored Python 3.x compatibility

-------------------

Features added
^^^^^^^^^^^^^^

* Extended and corrected the documentation and Jupyter notebook tutorials on
basic usage electronegativities, plotting and tables

Bugs fixed
^^^^^^^^^^

* Corrected ``raise`` to ``return`` when calling ``en_sanderson`` from
``electronegativity``
* Fixed and tested the formula for calculating the Li and Xue scale of
electronegativity in ``en_lie-xue``

-------------------

Features added
^^^^^^^^^^^^^^

* Added new vdW radii: ``vdw_radius_batsanov``, ``vdw_radius_bondi``,
``vdw_radius_dreiding``, ``vdw_radius_mm3``, ``vdw_radius_rt``,
``vdw_radius_truhlar``, ``vdw_radius_uff``
* Added an option to plot the long (wide) version of the periodic table in
``periodic_plot``

Bugs fixed
^^^^^^^^^^

* Typos in the docstrings