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

mosaicing function adding function to produce accuracy metric surface from tile RMSE

testing extent macthing option for region 4

adding extent option to main global mosaicing script

modifying python merge mosaicing option

adding match extent option to mosaicing