Add explicit support for namespace packages.

Fixes work that I'm trying out with new packages which I want to be in
the tcod namespace.

Author: HexDecimal

CHANGELOG.md

@@ -4,6 +4,9 @@ Changes relevant to the users of python-tcod are documented here.
 This project adheres to [Semantic Versioning](https://semver.org/) since version `2.0.0`.
 
 ## [Unreleased]
+### Added
+- Added explicit support for namespace packages.
+
 ### Changed
 - Using `libtcod 1.23.1`.
 - Bundle `SDL 2.26.0` on Windows and MacOS.

tcod/__init__.py

@@ -10,6 +10,9 @@
 
 import sys
 import warnings
+from pkgutil import extend_path
+
+__path__ = extend_path(__path__, __name__)
 
 from tcod import bsp, color, console, context, event, image, los, map, noise, path, random, tileset
 from tcod.console import Console  # noqa: F401