Updated Makefile clean target

This expands the clean target to clean up more stuff.

Makefile

@@ -21,8 +21,26 @@ docs: build
 	cp Changelog docs/changelog.rst
 	tox -edocs
 
-clean: clean-venv  ## Clean out any build artifacts to start over
-	rm -rf dist/*
+clean: clean-build clean-pyc clean-test ## remove all build, test, coverage and Python artifacts
+
+clean-build: ## remove build artifacts
+	rm -fr build/
+	rm -fr dist/
+	rm -fr .eggs/
+	find . -name '*.egg-info' -exec rm -fr {} +
+	find . -name '*.egg' -exec rm -f {} +
+
+clean-pyc: ## remove Python file artifacts
+	find . -name '*.pyc' -exec rm -f {} +
+	find . -name '*.pyo' -exec rm -f {} +
+	find . -name '*~' -exec rm -f {} +
+	find . -name '__pycache__' -exec rm -fr {} +
+
+clean-test: ## remove test and coverage artifacts
+	rm -fr .tox/
+	rm -f .coverage
+	rm -fr htmlcov/
+	rm -fr .pytest_cache
 
 test: dev  ## Run all the tox tests
 	tox -p all