Allows external rendering of other filetypes 2 (#8300)

* allow external rendering of other filetypes

fixes #4996 and #7614 
allows rendering of non-tex files, or otherwise accounted for filetypes

* Moves flie-size check before read()

And performs gofmt -s

* Only reads if markType is detected

routers/repo/view.go

@@ -346,6 +346,20 @@ func renderFile(ctx *context.Context, entry *git.TreeEntry, treeLink, rawLink st
 		ctx.Data["IsAudioFile"] = true
 	case base.IsImageFile(buf):
 		ctx.Data["IsImageFile"] = true
+	default:
+		if fileSize >= setting.UI.MaxDisplayFileSize {
+			ctx.Data["IsFileTooLarge"] = true
+			break
+		}
+
+		if markupType := markup.Type(blob.Name()); markupType != "" {
+			d, _ := ioutil.ReadAll(dataRc)
+			buf = append(buf, d...)
+			ctx.Data["IsMarkup"] = true
+			ctx.Data["MarkupType"] = markupType
+			ctx.Data["FileContent"] = string(markup.Render(blob.Name(), buf, path.Dir(treeLink), ctx.Repo.Repository.ComposeMetas()))
+		}
+
 	}
 
 	if ctx.Repo.CanEnableEditor() {