add Route.RemoveMiddleware method

Useful when all routes under a Party accept a middleware with some exceptions.

For Party-level use its Reset method instead, unless otherwise requested

HISTORY.md

@@ -28,6 +28,27 @@ The codebase for Dependency Injection, Internationalization and localization and
 
 ## Fixes and Improvements
 
+- Add the new `Party.UseOnce` method to the `*Route` too and a new `*Route.RemoveMiddleware(interface{})` method was added in order to remove a specific middleware from a specific Route. Example:
+
+```go
+func middleware(ctx iris.Context) {
+    // [...]
+}
+
+func main() {
+    app := iris.New()
+
+    // Register the middleware to all matched routes.
+    app.Use(middleware)
+
+    // Handlers = middleware, other
+    app.Get("/", index)
+
+    // Handlers = other
+    app.Get("/other", other).RemoveMiddleware(middleware)
+}
+```
+
 - Redis Driver is now based on the [go-redis](https://github.com/go-redis/redis/) module. Radix and redigo removed entirely. Sessions are now stored in hashes which fixes [issue #1610](https://github.com/kataras/iris/issues/1610). The only breaking change on default configuration is that the `redis.Config.Delim` option was removed. The redis sessions database driver is now defaults to the `&redis.GoRedisDriver{}`. End-developers can implement their own implementations too. The `Database#Close` is now automatically called on interrupt signals, no need to register it by yourself.
 
 - Add builtin support for **[i18n pluralization](https://github.com/kataras/iris/tree/master/_examples/i18n/plurals)**. Please check out the [following yaml locale example](https://github.com/kataras/iris/tree/master/_examples/i18n/plurals/locales/en-US/welcome.yml) to see an overview of the supported formats.

core/router/route.go

@@ -138,6 +138,39 @@ func (r *Route) Use(handlers ...context.Handler) {
 	r.beginHandlers = append(r.beginHandlers, handlers...)
 }
 
+// UseOnce like Use but it replaces any duplicate handlers with
+// the new ones.
+// Should be called before Application Build.
+func (r *Route) UseOnce(handlers ...context.Handler) {
+	r.beginHandlers = context.UpsertHandlers(r.beginHandlers, handlers)
+}
+
+// RemoveMiddleware deletes a begin handler based on its
+// name or the handler pc function.
+// Should be called before Application Build.
+func (r *Route) RemoveMiddleware(nameOrHandler interface{}) {
+	handlerName := ""
+	switch h := nameOrHandler.(type) {
+	case string:
+		handlerName = h
+	case context.Handler:
+		handlerName = context.HandlerName(h)
+	default:
+		panic(fmt.Sprintf("remove begin handler: unexpected type of %T", h))
+	}
+
+	var newHandlers context.Handlers
+	for _, h := range r.beginHandlers {
+		if context.HandlerName(h) == handlerName {
+			continue
+		}
+
+		newHandlers = append(newHandlers, h)
+	}
+
+	r.beginHandlers = newHandlers
+}
+
 // Done adds explicit finish handlers to this route.
 // Alternatively the end-dev can append to the `Handlers` field.
 // Should be used before the `BuildHandlers` which is