Restructure markup & markdown to prepare for multiple markup language… (#2411)

* restructure markup & markdown to prepare for multiple markup languages support

* adjust some functions between markdown and markup

* fix tests

* improve the comments

routers/init.go

@@ -16,7 +16,7 @@ import (
 	"code.gitea.io/gitea/modules/indexer"
 	"code.gitea.io/gitea/modules/log"
 	"code.gitea.io/gitea/modules/mailer"
-	"code.gitea.io/gitea/modules/markdown"
+	"code.gitea.io/gitea/modules/markup"
 	"code.gitea.io/gitea/modules/setting"
 	"code.gitea.io/gitea/modules/ssh"
 	macaron "gopkg.in/macaron.v1"
@@ -50,8 +50,8 @@ func GlobalInit() {
 
 	if setting.InstallLock {
 		highlight.NewContext()
-		markdown.InitMarkdown()
-		markdown.NewSanitizer()
+		markup.Init()
+
 		if err := models.NewEngine(migrations.Migrate); err != nil {
 			log.Fatal(4, "Failed to initialize ORM engine: %v", err)
 		}