Ruyaml

- fix for issue 82, deepcopy not working (reported by code monk)

- fix for comments after empty (null) values (reported by dsw2127 and cokelaer)

- optimisations on memory usage when loading YAML from large files (py3 -50%, py2 -85%)

- if ``load()`` or ``load_all()`` is called with only a single argument
(stream or string)
a UnsafeLoaderWarning will be issued once. If appropriate you can surpress this
warning by filtering it. Explicitly supplying the ``Loader=ruamel.yaml.Loader``
argument, will also prevent it from being issued. You should however consider
using ``safe_load()``, ``safe_load_all()`` if your YAML input does not use tags.
- allow adding comments before and after keys (based on
`StackOveflow Q&A <http://stackoverflow.com/a/40705671/1307905>`_ by
`msinn <http://stackoverflow.com/users/7185467/msinn>`_)

- another fix for numpy (re-reported independently by PaulG & Nathanial Burdic)

- only the RoundTripLoader included the Resolver that supports YAML 1.2
now all loaders do (reported by mixmastamyk)