Dtools.datastructures

* added __eq__ method to Stack class
* added some preliminary tests
* more tests are needed
* worst case O(n)
* will short circuit fast if possible

* decided base package should have no dependencies other than
* Python version (>=2.10 due to use of Python match statement)
* Python standard libraries
* made pytest an optional \[test\] dependency
* added src/ as a top level directory as per
* https://packaging.python.org/en/latest/tutorials/packaging-projects/
* could not do the same for tests/ if end users are to have access

* first Version uploaded to PyPI
* https://pypi.org/project/grscheller.datastructures/
* Install from PyPI
* $ pip install grscheller.datastructures==0.2.1.0
* $ pip install grscheller.datastructures for top level version
* Install from GitHub
* $ pip install git+https://github.com/grscheller/datastructuresv0.2.1.0
* pytest made a dependency
* useful & less confusing to developers and end users
* good for systems I have not tested on
* prevents another pytest from being picked up from shell $PATH
* using a different python version
* giving "package not found" errors
* for CI/CD pipelines requiring unit testing

* First version able to be installed from GitHub with pip
* $ pip install git+https://github.com/grscheller/datastructuresv0.2.0.2

* First failed attempt to make package installable from GitHub with pip

* BREAKING API CHANGE!!!
* Stack push method now returns reference to self
* Dqueue pushL & pushR methods now return references to self
* These methods used to return the data being pushed
* Now able to "." chain push methods together
* Updated tests - before making API changes
* First version to be "released" on GitHub