Most changes are fairly minor, including /close #32 (closed)
In Functions notebook, a more detailed explanation about declaration and definition has been added.
Update some data to reflect 2022 standpoint
Add Coliru links when stuff that worked in 2021 is broken in Xeus-Cling circa 2022
I hope I haven't broken anything - I made the first version of a branch following !35 (closed) and had to backport my modifications in the more senseful hierarchy used in main branch (I will take a Linux laptop for my rereading / modifications of the hands ons).
