Do not display empty user messages in chat mode.

There doesn't seem to be much value to them - they just take up space while also making it seem like there's still some sort of pseudo-dialogue going on, instead of a monologue by the bot.

modules/html_generator.py

@@ -142,7 +142,8 @@ def generate_chat_html(history, name1, name2, character):
               </div>
             """
 
-        if not (i == len(history)-1 and len(row[0]) == 0):
+        if not row[0]:  # don't display empty user messages
+            continue
         output += f"""
               <div class="message">
                 <div class="circle-you">