testing code on NEX for accuracy metrics kriging of resiudals and gdalmerge modified script

mosaicing script adding functions relevant to accuracy and residuals surface kriging

more modifications for mosaicing of functions for residuals, test for several days

testing accuracy function in the main script with data_s and data_v, training and testing

testing autokrige function for residuals of stations

modifying function script to add kriging function for residuals of predictions at stations

adding option to create residuals surface from stations using kriging

slight changes to mosaicing script to account for added parameters and testing

debugging of accuracy metric function from tile

adding accuracy metric function to main script and testing