Changes in version 0.1.0                        

  - Initial CRAN release.
  - Implemented calculateMoonlightIntensity() function for predicting
    moonlight intensity on the ground for any given place and time.
  - Implemented calculateMoonlightStatistics() function for calculating
    nightly statistics of moonlight illumination and moon phase.
  - Added elevExtCoeff() function to calculate extinction coefficient
    based on elevation.
  - Incorporated twilight illumination prediction.