ET0MassModels 1.0.0

• Initial release of the mass transfer-based ET0 models package.
• 10 mass transfer-based empirical ET0 models (Dalton, Trabert, Meyer, Rohwer, Penman, Albrecht, WMO, Brockamp-Wenner, Romanenko, Mahringer).
• FAO Penman-Monteith standard method as reference/base model.
• 9 statistical evaluation metrics (NSE, d, MSE, RMSE, NRMSE, MAE, MBE, r, R-squared).
• Visualization functions: scatter plots, Taylor diagrams, monthly comparison plots, annual bar charts.
• Sample meteorological dataset from a semi-arid region in India (Jhansi).
• Helper functions for solar geometry, vapor pressure, and other intermediate calculations.