Housekeeping is a Python package designed to make it easy for projects

to mark consumed code as deprecated or pending deprecation, with helpful

instructions for consumers using deprecated functionality.
It's built with the lessons we learned in Review Board, Djblets, and

RBTools.
There are two categories of warnings:


Deprecation warnings, which mark code as being deprecated and

  scheduled for removal in a specific upcoming version.


Pending deprecation warnings, which mark code as being available but

  scheduled to be deprecated in an unknown future version. Projects

  should later transition these to full deprecation warnings.


Deprecation warnings are backed by BaseRemovedInWarning, and

pending deprecation warnings are backed by BasePendingRemovalWarning.
Projects should subclass these to make their own base classes, filling

in the product field to specify their project's name. Subclasses of

their "removed in" deprecation warning class should then be created for

any versions in which functionality will be deprecated.
These classes can be passed to any Housekeeping function. Suitable

deprecation messages will be generated automatically.
Projects can also emit deprecation warnings themselves through the

.warn() function on the class.
This change introduces the base packaging, development setup, and base

warning classes. Upcoming changes will introduce deprecation helpers

that work with these classes.

Tested packaging and installing.
Tested with in-progress deprecation helpers.
Viewed the README in a GitHub-compatible Markdown viewer.