Add flag -v

This change adds a new flag `-v` to show instafeed version.

Makefile

@@ -1,4 +1,8 @@
+# Note: git tags *must* be annotated for this to work
+VERSION := $(shell git describe --tags `git rev-list --tags --max-count=1` | sed 's/^[^0-9]*//')
+
 all: instafeed
 
 instafeed:
-	@go build -mod=vendor
+	@go build -mod=vendor -ldflags "-s -w -X main.version=$(VERSION)" -o instafeed
+

instafeed.go

@@ -22,6 +22,9 @@ var (
 	configFile   string
 	listFile     string
 	feedMaxItems int
+	showVersion  bool
+
+	version string
 )
 
 func init() {
@@ -32,8 +35,14 @@ func init() {
 	flag.StringVar(&configFile, "f", path.Join(os.Getenv("HOME"), ".instafeed"),
 		"Path to file where to store profile configuration")
 	flag.StringVar(&listFile, "l", "", "Path to file containing list of Instagram users")
+	flag.BoolVar(&showVersion, "v", false, "Show version and exit")
 	flag.IntVar(&feedMaxItems, "n", 20, "Number of user feed items")
 	flag.Parse()
+
+	if showVersion {
+		fmt.Println("instafeed", version)
+		os.Exit(0)
+	}
 }
 
 func main() {