adding python script option from gdal modified merged Alberto

testing mask and python path on Atlas

adding mask option debugging

function mosaicing adding mask and path to python/gdal binaries

testing code on NEX with python mosaicing script from Alberto

more modifications to mosaicing function

script mosaicing function, adding raster accuracy metric funtion

running mosaicing script for accuracy metric mosaic, clean up

testing accuracy metric function and mosaic

creating function to produce accuracy metric raster for eact tile