Bugfix/examples

[tgrandje]

Update some examples from the doc:

• remove geofrdataframes and transform
• update code with latest numpy/pandas versions
• remove outdated references to API keys
• use pynsee to download latest IRIS dataset with built-in functions
• refacto a bit of code (mostly due to the IRIS dataset's slight changes)
• update some colormaps to be more "colorblind-friendly" and switch to monochrome palettes when deemed appropriate*

* that being said: de gustibus and so on... : so if you disagree with the new palettes, no problem for setting it back!