reorganization of _examples and add some new examples such as iris+groupcache+mysql+docker

Former-commit-id: ed635ee95de7160cde11eaabc0c1dcb0e460a620

_examples/request-body/read-msgpack/main.go

@@ -0,0 +1,37 @@
+package main
+
+import "github.com/kataras/iris/v12"
+
+// User example struct to bind to.
+type User struct {
+	Firstname string `msgpack:"firstname"`
+	Lastname  string `msgpack:"lastname"`
+	City      string `msgpack:"city"`
+	Age       int    `msgpack:"age"`
+}
+
+// readMsgPack reads a `User` from MsgPack post body.
+func readMsgPack(ctx iris.Context) {
+	var u User
+	err := ctx.ReadMsgPack(&u)
+	if err != nil {
+		ctx.StopWithError(iris.StatusBadRequest, err)
+		return
+	}
+
+	ctx.Writef("Received: %#+v\n", u)
+}
+
+func main() {
+	app := iris.New()
+	app.Post("/", readMsgPack)
+
+	// POST: http://localhost:8080
+	//
+	// To run the example, use a tool like Postman:
+	// 1. Body: Binary
+	// 2. Select File, select the one from "_examples/response-writer/write-rest" example.
+	// The output should be:
+	// Received: main.User{Firstname:"John", Lastname:"Doe", City:"Neither FBI knows!!!", Age:25}
+	app.Listen(":8080")
+}