[FEAT] Add a unique image mode for Dataref_water project

[NICOLAS-GAEL]

The chain has been modified to compute a mask on a single image with a configurable resolution. Moreover one additional band, the slope, is now computed and added in the composite product generated in input by ALCD. Some VRT files are created to consult easily the NDVI, NDWI and RGB images. It is also possible to take samples without buffer zone around. Processing time enhancement ("in memory" process for intermediate files, RAM parameter for OTB application, some files no more generated -contour_labels.tif, contours_superposition.png, colorized_classif.png, quicklook.png-, confidence map generation in option).