Twitch chat now supports subscriptions

- refactored code to be cleaner and more modularized

Updated scrolling on twitch chat to actually scroll to the bottom with new messages

Fast forwarding in videos with a twitch chat is now faster and provides a smoother transition

src/app/components/twitch-chat/twitch-chat.component.html

@@ -1,7 +1,8 @@
 <div class="chat-container" #scrollContainer *ngIf="visible_chat">
     <div style="width: 250px; text-align: center;"><strong>Twitch Chat</strong></div>
-    <div style="max-width: 250px" *ngFor="let chat of visible_chat">
+    <div #chat style="max-width: 250px" *ngFor="let chat of visible_chat; let last = last">
         {{chat.timestamp_str}} - <strong [style.color]="chat.user_color ? chat.user_color : null">{{chat.name}}</strong>: {{chat.message}}
+        {{last ? scrollToBottom() : ''}}
     </div>
 </div>