create the new FileServer and HandleDir, deprecate the rest APIBuilder/Party static methods and more

relative: https://github.com/kataras/iris/issues/1283 and removing pongo2 from vendor: https://github.com/kataras/iris/issues/1284

Former-commit-id: 3ec57b349f99faca2b8e36d9f7252db0b6ea080d

_examples/view/template_django_0/main.go

@@ -0,0 +1,44 @@
+package main
+
+import (
+	"time"
+
+	"github.com/kataras/iris"
+
+	// optionally, registers filters like `timesince`.
+	_ "github.com/flosch/pongo2-addons"
+)
+
+var startTime = time.Now()
+
+func main() {
+	app := iris.New()
+
+	tmpl := iris.Django("./templates", ".html")
+	tmpl.Reload(true)                             // reload templates on each request (development mode)
+	tmpl.AddFunc("greet", func(s string) string { // {{greet(name)}}
+		return "Greetings " + s + "!"
+	})
+
+	// tmpl.RegisterFilter("myFilter", myFilter) // {{"simple input for filter"|myFilter}}
+	app.RegisterView(tmpl)
+
+	app.Get("/", hi)
+
+	// http://localhost:8080
+	app.Run(iris.Addr(":8080"), iris.WithCharset("UTF-8")) // defaults to that but you can change it.
+}
+
+func hi(ctx iris.Context) {
+	// ctx.ViewData("title", "Hi Page")
+	// ctx.ViewData("name", "iris")
+	// ctx.ViewData("serverStartTime", startTime)
+	// or if you set all view data in the same handler you can use the
+	// iris.Map/pongo2.Context/map[string]interface{}, look below:
+
+	ctx.View("hi.html", iris.Map{
+		"title":           "Hi Page",
+		"name":            "iris",
+		"serverStartTime": startTime,
+	})
+}