Daylength Function

This function plots the Daylength (hours) for a year-round due to Latitude input.
Input: Latitude [degrees]
Output: Minimum daylength, maximum daylength and year daylength plot

Based on:
W. Forsythe, E. Rykiel, R. Stahl, H. Wu and R. Schoolfield, "A model comparison for daylength as a function of latitude and day of year", Ecological Modelling, vol. 80, no. 1, pp. 87-95, 1995.