Add the Sun, Moon, and Pluto

• Adds the capability to compute the geocentric position of the Sun and Moon.
• Adds the heliocentric and geocentric position of Pluto.

Adds geocentric positions of planets

This release adds functionality to calculate the geocentric apparent right ascension and declination of the planets at a given date/time.

Add MIT license.

0.0.4

Create LICENSE.md

Minor improvement to unit test coverage.

0.0.3

Improve tests for time data structure

0.0.2

Added the Yale Bright Star Catalog, improvements to the representation of units (time, distance, angle).

0.0.1

Compute heliocentric positions of the planets.