added parallel make support

Makefile

 .PHONY: tests output pylint2 pylint3
 
-IGNORED_PYLINT_TESTS=invalid-name,missing-docstring,redefined-variable-type,too-few-public-methods
+IGNORED_PYLINT_TESTS=invalid-name missing-docstring \
+	redefined-variable-type too-few-public-methods
 IGNORED_PYLINT2_TESTS=superfluous-parens
+IGNORED_PYLINT3_TESTS=
 
-tests: output pylint2 pylint3
+tests:
+	@make -j 3 output pylint2 pylint3
 	# all ok
 
 output:
 	# testing python script output
-	@set -e;\
+	@set -e; \
 	TEMP=`mktemp`; \
 	trap 'rm $$TEMP' EXIT; \
 	for FILE in *.py; do \
-		printf '%s\n' "$$FILE"; \
+		printf 'output test:\t%s\n' "$$FILE"; \
 		if [ -e "$$FILE.out" ]; then \
 			python "$$FILE" > $$TEMP; \
 			diff "$$FILE.out" $$TEMP; \
@@ -22,11 +25,19 @@ output:
 		fi; \
 	done
 
+COMMA:=,
+EMPTY:=
+SPACE:=$(EMPTY) $(EMPTY)
+PYLINT2_OPTIONS=--disable=$(subst $(SPACE),$(COMMA),\
+	$(IGNORED_PYLINT_TESTS) $(IGNORED_PYLINT2_TESTS))
+PYLINT3_OPTIONS=--disable=$(subst $(SPACE),$(COMMA),\
+	$(IGNORED_PYLINT_TESTS) $(IGNORED_PYLINT3_TESTS))
+
 pylint2:
-	# testing the python scripts via pylint
+	# testing python scripts via pylint2
 	@for FILE in *.py; do \
-		printf '%s\n' "$$FILE"; \
-		REPORT="$$(pylint --disable=$(IGNORED_PYLINT_TESTS),$(IGNORED_PYLINT2_TESTS) "$$FILE" 2>&1)"; \
+		printf 'pylint2 test:\t%s\n' "$$FILE"; \
+		REPORT="$$(pylint $(PYLINT2_OPTIONS) "$$FILE" 2>&1)"; \
 		if ! [ $$? = 0 ]; then \
 			printf '%s\nThe above report is for file "%s".\n' "$$REPORT" "$$FILE"; \
 			exit 1; \
@@ -34,10 +45,10 @@ pylint2:
 	done
 
 pylint3:
-	# testing the python scripts via pylint3
+	# testing python scripts via pylint3
 	@for FILE in *.py; do \
-		printf '%s\n' "$$FILE"; \
-		REPORT="$$(pylint3 --disable=$(IGNORED_PYLINT_TESTS) "$$FILE" 2>&1)"; \
+		printf 'pylint3 test:\t%s\n' "$$FILE"; \
+		REPORT="$$(pylint3 $(PYLINT3_OPTIONS) "$$FILE" 2>&1)"; \
 		if ! [ $$? = 0 ]; then \
 			printf '%s\nThe above report is for file "%s".\n' "$$REPORT" "$$FILE"; \
 			exit 1; \