QuanSight work showcase

[CommonClimate]

Going with Pyleoclim release 0.11.0, we need to showcase the multiple improvements brought about by the work of the QuanSight team.

• all tutorials should start using load_dataset() whenever possible
• the pandas work per se should go into a dedicated L0 notebook called "Pandas in Pyleoclim". This will repurpose the first half of the paleopandas playground.
• the work on MultipleSeries overloaded methods (+, -, &) should go into “L0_basic_MSES_manipulation.ipynb”. This will repurpose the second half of the paleopandas playground

[CommonClimate]

done in #24