Fix bugs following geoutils update

[adehecq]

Because of the MemoryFile PR in geoutils, several attributes of Raster objects do not exist. Fix bugs that arise with that change. Things important to keep in mind:

• the rasterio DatasetReader initially accessed with self.ds was removed
• the method self._get_rio_attrs was removed
• the method self._update was removed

Fixed several issues, but I still have a few that fail locally:

• tests/test_docs.py::TestDocs::test_build -> don't understand why
• tests/test_fit.py::TestRobustFitting::test_robust_sumsin_fit -> fail with AssertionError @rhugonnet do you want to check?
• tests/test_spatialstats.py::TestVariogram::test_sample_multirange_variogram_default -> @rhugonnet?
• xdem/terrain.py::xdem.terrain.slope -> there is some rounding error in the docstring. Not sure how we can set the threshold for doc checks.

[rhugonnet]

Good news: most of these tests you mention don't fail on the CI.
Two reasons:

• Need to overwrite your example files locally,
• Need to update your environment (this will surely fix the tests/test_fit.py::TestRobustFitting::test_robust_sumsin_fit, which used to fail randomly but not anymore, see Basinhopping randomly fails in CI #209)

Bad news: the different value for variograms is also an issue in the CI, and I don't understand that one yet.
Edit: I have the source. The variogram test didn't fail locally first. I deleted the Longyearbyen data/ and processed/, and now it fails. Something has changed in how we process the data into a dDEM, in the coreg surely, now need to find it (and better tests for coreg...)
Edit: noticing something weird with the nodata of our examples: NoData Value: -3.4028234663852886e+38 (ah no, apparently that's the right value from gdalinfo)
Ah but, yeah, looks like the ddem of the example files is full of slightly modified nodata:

ddem.data.data[0, 0, 0]
3.4028235e+38
ddem.data.data[0, 0, 0] == ddem.nodata
False

[rhugonnet]

OK, so I added test_example.py with two functions that tests the example data to see if it stays the same. This is in particular to test if the data we process and store as examples (to avoid processing multiple times) stays the same. The data we fetch from xdem-data should never change, but now we'll be sure of it too 😄.

I ran the test changing from geoutils==0.0.8 to after the MemoryFile PR. The values of the arrays were still the same, but the nodata in the ddem array were not. They change from 2316 points with nodata (before MemoryFile PR) to 0 after.

In the examples.py that creates this ddem example file, I noticed the processing with theNuthKaab() was still written old-school (before we changed nodate handling in GeoUtils). Changing it to the current syntax seems to have solved it!

What a run it was to track this one! I hope test_examples.py will prevent this issue in the future 😅

[rhugonnet]

Tests finally passing, in the end it was a rasterio issue with >1.3. Opened GlacioHack/geoutils#293 and we'll have to create a reproducible example to open an issue there as well.