added a pylint tester

.PHONY: test

test:

	# Testing the python files via pylint3.

	@for FILE in *.py; do \

		REPORT="$$(pylint3 --disable=invalid-name,missing-docstring "$$FILE" 2>&1)"; \

		if ! [ $$? = 0 ]; then \

			printf '%s\nThe above report is for file "%s".\n' "$$REPORT" "$$FILE"; \

			exit 1; \

		fi; \

	done; \

	printf 'All OK.\n'