astronomyengine 0.1.0

Initial CRAN release of astronomyengine package

New features

• R bindings to the Astronomy Engine C library, providing accurate astronomical calculations
• Support for calculating positions of the Sun, Moon, and planets
• Single-file header + source bundling of the Astronomy Engine C library for use by other R packages via LinkingTo
• Accuracy of approximately ±1 arcminute based on the VSOP87 planetary model
• Full support for location-based calculations based on longitude, latitude, and height
• POSIXct time input for all functions with UTC timezone support