Add standalone chat with ability to send messages (#1270)

* properly pass the messagesOnly to chat

* use actual username if embed is not messageonly

* mv embed chat to chat-overlay

* add new embed chat page

* fix router

* secure random number for non-secure application!

* add chat enable/disable functionality

* add username form

add customStyles

* mv overlay css

* add style for embed chat

style cleanup

* rm username form from chat overlay

* refactoring

* css cleanup

css adjust

* minor cleanup

* mark the embed chats as readonly and readwrite

* replace 301 redirects with 307

* add redirect for the cached address

* set insatnce name in chat

webroot/styles/standalone-chat-readonly.css

@@ -0,0 +1,50 @@
+/*
+Example/Suggested custom CSS settings to set in OBS.
+///
+html { margin: 0px; padding: 20px; background-color: rgba(0,0,0,0.5); font-size: 24px; }
+///
+This one will add some space around box, give it a semi-transparent dark background; and increase the overall to a base unit of 24px.
+
+You may change any of these settings to fit your presentation layout. Note that the overall message text color is white.
+*/
+
+/*
+The styles in this file mostly ovveride those coming from chat.css
+*/
+
+/* modify this px number if you want things to be relatively bigger or smaller */
+#messages-only {}
+
+::-webkit-scrollbar {
+  width: 0px;
+  background: transparent;
+}
+
+#messages-only #messages-container {
+  height: 100%;
+  height: 100vh;
+  overflow: auto;
+}
+#messages-only .message-content {
+  text-shadow: 1px 1px 0px rgba(0,0,0,0.25);
+}
+#messages-only .message {
+  padding: .5em;
+}
+
+#messages-only .message-text {
+  font-weight: 400;
+  color: white;
+}
+#messages-only .message-text a {
+  color: #fc0;
+}
+#messages-only .message-author {
+  color: rgba(20,0,40,1);
+}
+
+#messages-only .message-text .chat-embed,
+#messages-only .message-text .instagram-embed,
+#messages-only .message-text .embedded-image {
+  max-width: 350px;
+}