Dtools.fp

* much work dtools.iterables
* finally implemented scReduceL and scReduceR functions
* tweaked API across iterables module
* added two state changing methods to dtools.err_handling.MB
* added put method to MB class
* if MB is empty, injects a value into it
* otherwise, do nothing
* added pop method to MB class
* if MB is not empty, remove the value and return it
* otherwise, raise ValueError
* found both methods useful to treat a MB just as a container
* avoid using these methods in pure code

* added class method sequence to class State

* Repo name changes
* GitHub: fp -> dtools-fp
* PyPI: grscheller.fp -> dtools.fp

* added modules lazy and state
* simplifications done to fp.iterables module
* renamed flatmap methods to bind
* minor MB and XOR updates/corrections

* added fp.function module
* combine and partially apply functions as first class objects
* some tests may be lacking

* breaking API changes, next PyPI release will be 1.1.0.
* renamed module `nothingness` to `singletons`
* split class NoValue into class NoValue and Sentinel
* `noValue` represents a missing value
* `_sentinel` is intended to provide a "private" sentinel value
* frees up `None` and `()` for application use
* avoids name collisions with user code
* will be used in grscheller.datastructures
* will redo docs in docs repo