-------------------
- Change default product to ``SRTM3`` as direct access to ``SRTM1`` has been apparently discontinued.
See issue `18 <https://github.com/bopen/elevation/issues/18>`_.
- Added ``-r/--reference`` and ``-m/--margin`` options to define the bounds from a GDAL/OGR data source.
Install the ``rasterio`` and ``fiona`` packages with ``pip`` to enable it.
Issue `14 <https://github.com/bopen/elevation/issues/14>`_.
- Enable reading defaults from environment variables prefixed with ``EIO``,
e.g. ``EIO_PRODUCT=SRTM3`` and ``EIO_CLIP_MARGIN=10%``.