GitLab

And also
- Remove test on uninitialized value
- Change the class to be const-correct

Many simplifications remain to be done.

TEST: Changing output data format to .img because gdal < 2.0 does not handle properly the AREA_OR_POINT georeferencing for tiff format

TEST: Gdal/Openjpeg driver limits overview report to 128x128 size, and interpolate smaller overviews. Avoid comparing with baseline from openjpeg in this case

TEST: Gdal/Openjpeg driver limits overview report to 128x128 size, and interpolate smaller overviews. Avoid comparing with baseline from openjpeg in this case