avoid double resampling in mosaic creation

[jguinet]

a gdal_merge.py should should be preferred.

on the ortho creation the target resolution and nodata should be set. for a 10 meter band for example

    gdalwarp \\
        SENTINEL2_L1B_WITH_GEOLOC:./$XML:$VRT \\
        "$OUT" \\
        -t_srs EPSG:{UTM_EPSG} \\
        -te {LOCATION["ul_x"]} {LOCATION["lr_y"]} {LOCATION["lr_x"]} {LOCATION["ul_y"]} \\
        -r cubic \\
        -tr 10 -10 \\
        -co COMPRESS=LZW \\
        -co TILED=YES \\
        -dstnodata 0 \\
        -overwrite

then gdal_merge.py will automatically create the mosaic without resampling

[aburie-cs]

Closed by #63