Tweak Sphinx config to build on ReadTheDocs.
Hard-code version in docs/source/conf.py to avoid having to import neurokernel during docs build.
Don't set html_theme_path when building on RTFD.
No need for plot_directive when building docs.
Add introduction to docs, add mock mechanism to conf.py.
Mock more modules in docs config to placate autodoc.
Reorganize reference docs, include (almost) all classes/functions.
Tweak installation instructions.
Add link to RTD site to README.rst.
msgpack_numpy -> msgpack-numpy.
Add msgpack to list of modules to mock in conf.py.
Update numpydoc to 0.5.
Set numpydoc_show_class_members to False.
added photereceptor class (needs changes)