[a.pyIterableR3] Accept a Python sequence instead of an R3 instance (#111)

Merging branch 'a.pyIterableR3'  into 'main'.

A SWIG `typemap` is added to map a Python sequence to an `R3` instance (`Wrap/Swig/r3_typemap.i`).


Note that this method works only for functions or methods which are _not_ overloaded. Overloaded functions or methods must be _explicitly_ 'extended' in SWIG to accept a Python sequence instead of an `R3` instance.
See <https://www.swig.org/Doc1.3/Typemaps.html#Typemaps_overloading>.

Additionally, the code is improved to avoid copying `R3` arguments when possible.
A const reference is used instead.

Related to issue #111


See merge request !2766