Add NASADEM SRTM revision when available

[alexamici]

Proposed by Nicolas Cadieux here: https://lists.osgeo.org/pipermail/qgis-user/2016-March/035876.html

NASADEM ami to be a "state-of-the-art global digital elevation model (DEM) derived from a combination of Shuttle Radar Topography Mission (SRTM) processing improvements, elevation control, void-filling and merging with data unavailable at the time of the original SRTM production"

https://earthdata.nasa.gov/community/community-data-system-programs/measures-projects/nasadem

See also: http://www2.jpl.nasa.gov/srtm/

[der-stefan]

Let's wait for NasaDEM...

[der-stefan]

NasaDEM is said to be published end of 2017 [1].

[onnyyonn]

Is there any plan for adding this still?

[ashlinrichardson]

Would be great to have!