sunrise and sunset from pyephem

[cwhanse]

pvlib python pull request guidelines

Thank you for your contribution to pvlib python! You may delete all of these instructions except for the list below.

You may submit a pull request with your code at any stage of completion.

The following items must be addressed before the code can be merged. Please don't hesitate to ask for help if you're unsure of how to accomplish any of the items below:

• Addresses issue add sunrise / sunset to Location #114
• I am familiar with the contributing guidelines.
• Fully tested. Added and/or modified tests to ensure correct behavior for all reasonable inputs. Tests (usually) must pass on the TravisCI and Appveyor testing services.
• Updates entries to docs/sphinx/source/api.rst for API changes.
• Adds description and name entries in the appropriate docs/sphinx/source/whatsnew file for all changes.
• Code quality and style is sufficient. Passes LGTM and SticklerCI checks.
• New code is fully documented. Includes sphinx/numpydoc compliant docstrings and comments in the code where necessary.
• Pull request is nearly complete and ready for detailed review.

Brief description of the problem and proposed solution (if not already fully described in the issue linked to above):

[wholmgren]

would next_sun_rise_set_pyephem be more consistent with your preferred naming scheme?

[cwhanse]

Yes, I'll change. I have in mind Location.get_next_sunrise, Location.get_previous_sunrise as wrapper methods.

[stickler-ci]

E226 missing whitespace around arithmetic operator

[stickler-ci]

E226 missing whitespace around arithmetic operator

[stickler-ci]

E124 closing bracket does not match visual indentation

[stickler-ci]

E999 SyntaxError: can't delete function call

[cwhanse]

Sigh. PyEphem has the same behavior as spa. If, on a given day D, sunset occurs after midnight UTC of the next day D+1 (common in summer in northern hemisphere), pyephem's next_setting function will return D's sunset, not D+1 sunset, when passed D+1 even when localized. Why? PyEphem converts all dates to it's own integer system (days since 1899/12/31 12:00:00 UTC) without adjusting for the timezone offset, then finds the next sunset after the requested datetime.

[cwhanse]

Fixed the timezone behavior. Ready for review/approve/merge.

[wholmgren]

Looks good to me. You can resolve the merge conflict locally or in the web interface (click resolve conflicts and then delete the >>> --- <<< cruft). Usually github will automatically take the union of this file. Not sure why it's not working this time.

[wholmgren]

I went ahead and resolved the conflict. Merging...