GRASS: fill DEM by r.hydrodem instead of r.fill.dir

[landam]

• [x] update reference data
• [x] check if the extension is already installed

[landam]

Velvary comparision

diff (grass@master - grass@hydrodem)

diff (arcgis - grass@hydrodem)

No difference...

n: 2163396
minimum: 0
maximum: nan
range: nan
mean: 0