Heniautos

Added missing TSV data files and manifest

Complete refactor with many, many changes

* Removed hard dependency on Skyfield (but can be optionally used)
* Changed default approximation of visible new moon. Now 1 day after conjunction rather than 2 days
* Added calendars for other poleis (Corinth, Delphi, Delos, Sparta) and generation of generic calendars based on several parameters
* Some functions moved to sub-modules
* Documentation moved to sphinx and readthedocs.io

* Add `--full-moons` option to `heniautos` command to output full moon dates

* Add option to `heniautos` command to output Julian year with
indications of solar events and new moons

* Add options for all solar events (solstices, equinoxes) to `heniautos` command

Initial release