Introduce a Makefile for UNIX-style people

Signed-off-by: Shin'ya Minazuki <shinyoukai@laidback.moe>

Makefile

@@ -0,0 +1,18 @@
+GO ?= go
+GOFLAGS ?= -buildvcs=false -ldflags='-w -X code.laidback.moe/yuki.Version=1.0' -buildmode=exe -v
+PREFIX ?= /usr/local
+
+all: build
+
+build:
+	${GO} build ${GOFLAGS} -o yuki
+clean:
+	rm -f yuki
+install:
+	install -d ${DESTDIR}${PREFIX}/bin
+	install -d ${DESTDIR}${PREFIX}/man/man1
+	install -m0755 yuki ${DESTDIR}${PREFIX}/bin
+	install -m0660 yuki.1 ${DESTDIR}${PREFIX}/man/man1
+tidy:
+	${GO} mod tidy
+