Swift 5 Support

Cleans up some build warnings that cropped up and were failing Swift 5 CI builds.

Swift 4 Package Manager Support

Ephemeris already supported building against Swift 4.x, but now it supports the package manager natively. Because 4.2 is now issuing warnings around the Swift 3 package manager being deprecated, it is more important to make sure the new manifest is ready to go for when Swift 5 shows up.

Ready to Go Edition

Calculate:

Sunrise (Rise, Civil Twilight, Nautical Twilight, or Astronomical Twilight)
Moonrise
Moon Illumination

Fix Access Levels

0.1.1

Fix Some of the Access Levels

Calculate Lunar Illumination Edition

Can Calculate:

• RA/Dec of Moon or Sun for a given Date
• Illumination of the Moon for a given Date