improved AstronomicalCoordinates: 1. made properties immutable 2. made properties and functions public 3. added convenience initializers
improved AstronomicalCoordinates:
1. made properties immutable
2. made properties and functions public
3. added convenience initializers

onekiloparsec/SwiftAA,alex-vasenin/SwiftAA,alex-vasenin/SwiftAA,alex-vasenin/SwiftAA,alex-vasenin/SwiftAA,onekiloparsec/SwiftAA,onekiloparsec/SwiftAA,onekiloparsec/SwiftAA,onekiloparsec/SwiftAA,alex-vasenin/SwiftAA