gdal backwards compatibility

[skoulouzis]

From https://pypi.org/project/GDAL/

If you have previous code that imported the global module and still need to support the old import, a simple try…except import can silence the deprecation warning and keep things named essentially the same as before:

try:

...     from osgeo import gdal
... except ImportError:
...     import gdal

[jgomezdans]

Thanks for this, but I don't think this code is being updated/worked on anymore. Get in touch (j.gomez-dans at ucl.ac.uk) if you want to discuss.