Tests are organized as follows:

	tests/
		active tests
	tests/tests_unit/
		unit tests, can be invoked from `setup.py`

	tests_working/
		tests under development

Recommended debug settings

	export MD_DEBUG_STACKS_SIMPLE=1
	export MD_DEBUG_STACKS=1
	export MD_DEBUG_TOKENS=1
	export MD_TEST_PRINT_RESULTS=1
	 