Style fixes all around.
gdal.py: VRT.render() now uses BIGTIFF=IF_SAFER.

If the uncompressed size of the GeoTIFF is bigger than 2GB, GDAL will create
a BigTIFF.
Added tag version-1.2.0 for changeset 69d8b7d7c0c9
Added tag version-1.2.0 for changeset 2f00ad4ab2ec