Add Makefile: make dist, make test, make build

Makefile

@@ -0,0 +1,19 @@
+.PHONY: all build dist test install
+
+build:
+	@mkdir -p ./bin && rm -f ./bin/*
+	go build -o ./bin/yaml ./cmd/yaml
+
+dist:
+	@mkdir -p ./bin && rm -f ./bin/*
+	GOOS=darwin GOARCH=amd64 go build -o ./bin/yaml-darwin64 ./cmd/yaml
+	GOOS=linux GOARCH=amd64 go build -o ./bin/yaml-linux64 ./cmd/yaml
+	GOOS=linux GOARCH=386 go build -o ./bin/yaml-linux386 ./cmd/yaml
+	GOOS=windows GOARCH=amd64 go build -o ./bin/yaml-windows64.exe ./cmd/yaml
+	GOOS=windows GOARCH=386 go build -o ./bin/yaml-windows386.exe ./cmd/yaml
+
+test:
+	go test ./...
+
+install:
+	go install ./cmd/sup