Cpymad

- add MacOS wheels for the first time. These are still mostly experimental
and require Apple's Accelerate framework to be installed on the user machine.
- update documentation

- Update official support to ``MAD-X 5.02.11``

- fix crash due to incorrect parameter name for ``logging.basicConfig``
- fix crash due to missing ``subprocess.MAXFD`` on python3.5
- fix coverage report submitted to coveralls.io

Collecting further backward incompatibilities before the final 1.0 release, as
well as minor bugfixes.

- only execute variable updates if their value has changed
- use ``__slots__`` for Parameter
- remove cpymad-specific behaviour for ``Madx.select``
- allow direct access to MAD-X commands as attributes on the ``Madx`` instance
- rename ``Parameter.argument`` to ``Parameter.definition``
- add ``VarList.defs``, ``Command.defs`` instance variables for accessing the
definitions (provisional API)
- create the accessor proxies in advance
- disallow indexing ``ElementList`` by ``dict`` instances (i.e. by element
object)
- handle uppercase 'S' and 'E' in ``ElementList``

- expose all columns in table, don't limit by current selection
- unify the get_table_column_XXX functions in libmadx
- add Table.selected_columns method
- add Table.selected_rows method
- drop ability to build MAD-X through setup.py
- don't search for MAD-X in system locations
- simplifications in setup script
- replace runtime dependency on setuptools by importlib_resources

- read chkick/cvkick element attributes