0.1 documentation improvements

[wholmgren]

Summarizing and copying material from #16, this PR includes improvements to

Major:

• Add more to the homepage
• Add basic install instructions
• Link to Rob and Will's PVSC papers.
• Add What's new section. Closes Add What's New section to docs #8.
• Add comparison to PVLIB_MATLAB section.
• Describe the relation to PVPMC, PVLIB-Matlab, address some of the points raised in bring pvlib-python up to date with PVLIB-MATLAB 1.2 and 1.3 #2.
• Make a text link for the tutorials instead of my usual url dump.
• Different page for each module? I think not, at least for 0.1

Minor:

• Ineichen doesn’t provide info on single df output
• function is now aoi, but docs reference getaoi throughout, except in actual function doc
• lots of references to pvl_function not function
• The numpydoc convention is to avoid using "See also" unless it's really important. still not great, and many broken links, but I think good enough for 0.1
• The doc title capitalization needs to be updated.
• Copyright needs to be updated.
• pvlib.pvsystem.snlinverter has a long table that rtfd doesn't always format nicely small improvement, good enough
• References to maketimestruct, makelocationstruct in pvlib.clearsky.haurwitz, maybe more.
• pvlib.irradiance.beam_component has no documentation.
• All modules need a better introduction to what's in them. still not great, but I think good enough for 0.1
• pvlib.pvsystem.I_from_V has no documentation. only added warning that this may go private
• pvlib.pvsystem.Voc_optfcn has no documentation. only added warning that this may go private
• pvlib.pvsystem.calcparams_desoto says that module_parameters can be a Series, which, although true, is probably confusing. In any case, the doc's dict keys do not match the code's dict keys.
• Misspelling in pvlib.pvsystem.retrieve_sam example.
• Format equation in pvlib.pvsystem.singlediode
• Add sphinx.ext.extlinks for issue tracking in what's new. Copied from pandas.

Does not address

• pvlib.pvsystem.systemdef as described in meta, location, and systemdef philosophy #17
• pvlib.tmy.readtmy2 refers to a metadata struct instead of a dict. Addressed in TMY loading improvements #7.

Docs can be viewed here

Let me know if you think that the doc improvements are good enough for the 0.1 release or if you want to see further changes on this PR.

[bmu]

From my side, this is good for the 0.1 release.

[wholmgren]

I think we should give @Calama-Consulting a chance for feedback on this one.

[wholmgren]

@dacoex the github links are now working in the test build. I will go through and add more links in either this pull request or others depending on merge order.

[dacoex]

@wholmgren all fine.

[robwandrews]

This looks good, @wholmgren can you address the merge conflicts and I'll merge it

[wholmgren]

Ok, ready to merge. Closes #16.