Fix codeblocks in chat (#676)

* allowed codeblocks in chat (owncast#675)

* dont send empty chat messages back to frontend (owncast#675)

models/chatMessage.go

@@ -38,6 +38,10 @@ func (m *ChatEvent) RenderAndSanitizeMessageBody() {
 	m.Body = RenderAndSanitize(raw)
 }
 
+func (m *ChatEvent) Empty() bool {
+	return m.Body == ""
+}
+
 // RenderAndSanitize will turn markdown into HTML, sanitize raw user-supplied HTML and standardize
 // the message into something safe and renderable for clients.
 func RenderAndSanitize(raw string) string {
@@ -111,5 +115,9 @@ func sanitize(raw string) string {
 	// Allow emphasis
 	p.AllowElements("em")
 
+	// Allow code blocks
+	p.AllowElements("code")
+	p.AllowElements("pre")
+
 	return p.Sanitize(raw)
 }