Application API updated to include Application, for raw application type

retrieval; DestroyApplication, for destroying registered applications;
and removed SetParent, replacing it with SetMaster.

api.go

@@ -13,6 +13,8 @@ import (
 
 type Application interface {
 	AttachApplication(Application)
+	DestroyApplication(Application)
+	Application() *application
 	LoadSession()
 	BindGroup(path string) *RouterGroup
 	Bind(controller Controller) error
@@ -24,7 +26,7 @@ type Application interface {
 	DefaultMiddleware()
 	SetMiddleware(middleware ...func(http.Handler) http.Handler) Application
 	SetDefaultRenderer(renderer render.Renderer) Application
-	SetParent(app Application)
+	SetMaster(app Application)
 	RegisterShutdownHook(hook ShutdownHook)
 	Listen() error
 	Stop()