Dtools-fp

* removed woException `XOR` method
* `getDefaultRight(self) -> R`:
* added methods
* makeRight(self, right: R|Nada=nada) -> XOR[L, R]:
* swapRight(self, right: R) -> XOR[L, R]:

* fp.iterables no longer exports `CONCAT`, `MERGE`, `EXHAUST`
* for grscheller.datastructures
* grscheller.datastructures.ftuple
* grscheller.datastructures.split\_ends

* class Nothing re-added but renamed class Nada
* version grscheller.untyped.nothing for more strictly typed code

* forgot to update README.md on last PyPI release
* simplified README.md to help alleviate this mistake in the future

* from last PyPI release
* added accumulate function to fp.iterators
* new fp.nothing module implementing nothing: Nothing singleton
* represents a missing value
* better "bottom" type than either None or ()
* renamed fp.wo_exception to fp.woException
* overall much better docstrings

* replicated functionality from grscheller.datastructures
* grscheller.datastructures.fp.MB -> grscheller.fp.wo\_exception.MB
* grscheller.datastructures.fp.XOR -> grscheller.fp.wo\_exception.XOR
* grscheller.core.iterlib -> grscheller.fp.iterators