fresnel v0.7 release

[Joshua A. Anderson]

fresnel v0.7 is now available.

* conda-forge binary package: https://anaconda.org/conda-forge/fresnel
* Docker/singularity images: https://glotzerlab-software.readthedocs.io
* Source tarball: http://glotzerlab.engin.umich.edu/Downloads/fresnel
* git repository: http://github.com/glotzerlab/fresnel/
* Documentation: http://fresnel.readthedocs.io

Thank you to all who contributed. Please report issues and suggest
feature enhancements via the github repository
(http://github.com/glotzerlab/fresnel/). Please request support through
this mailing list.

v0.7.0 changes:

* Add ``util.convex_polyhedron_from_vertices``: compute convex
polyhedron plane origins and normals given a set of vertices
* Improve documentation
* Add ``interact.SceneView``: pyside2 widget for interactively rendering
scenes with path tracing
* Add ``geometry.Mesh``: Arbitrary triangular mesh geometry, instanced
with N positions and orientations
* **fresnel** development is now hosted on github:
https://github.com/glotzerlab/fresnel/
* Improve ``light.lightbox`` lighting setup
* API breaking changes:
* ``geometry.ConvexPolyhedron`` arguments changed. It now accepts
polyhedron information as a dictionary.

v0.7.1 changes

* Fix the conda-forge mac package
----
Joshua A. Anderson, Ph.D.
Research Area Specialist, Chemical Engineering, University of Michigan
http://www-personal.umich.edu/~joaander/