create ng bindings python namespace

[hobu]

from osgeo import gdal
from osgeo import osr
from osgeo import ogr
from osgeo import gdal_array
from osgeo import gdalconst

The following still work, but will report a DeprecationWarning:

import gdal
import osr
import ogr
import gdalconst

[hobu]

RFC: http://trac.osgeo.org/gdal/wiki/rfc17_python_namespaces

Most updates were done on 9/28/2007 during the FOSS4G sprint and are around r12276:r12278