Refactor CROP and load_rio()

[adebardo]

Context

Currently, the handling of region of interest (ROI) or crop geometry is split between _load_rio() and the crop() method. Which is hard to maintain.
We propose to delete the ROI management from _load_rio() and use the crop() method before calling _load_rio(), if a ROI is provided during raster initialization.

[adebardo]

@rhugonnet @vschaffn is this okay ?

[adehecq]

I fully agree we should merge the two, and the best choice is to move the ROI functionality into crop (see my comment in #642). Additionally, I would recommend sticking to one name, as keeping both ROI and crop adds confusion.