Grscheller.untyped

* Obsoleted PyPI project
* use grscheller.experimental instead
* corresponds to grscheller.experimental version 0.1.0
* decided to use with strict typing
* hence a name change was essential
* did not want to put back in grscheller.fp
* having both classes Nada and MB there redundant
* still want to preserve this implementation

* API change
* changed method name `Nada.nget` to `Nada.nada_get`
* a little more inconvenient, but less likely of a name collision

* renamed untyped.nothing to untyped.nada
* Nothing -> Nada
* nothing -> nada

* typing improvements back-ported from grscheller.fp
* updated optional dependencies to use grscheller.circular-array 3.4.0
* for tests/

* prototype of a module level inaccessible sentinel value
* _nothing_nada: _Nothing_Nada
* for use only within the grscheller.untyped module itself

* moved module nothing from grscheller.fp
* wanted everything in grscheller.fp strictly typed
* felt class Nothing worked better untyped
* at least marginally typed with Any