Add help command and command categories

src/main/java/wtf/beatrice/hidekobot/objects/commands/CommandCategory.java

@@ -0,0 +1,18 @@
+package wtf.beatrice.hidekobot.objects.commands;
+
+public enum CommandCategory
+{
+    MODERATION("️\uD83D\uDC40"),
+    FUN("\uD83C\uDFB2"),
+    TOOLS("\uD83D\uDEE0"),
+
+    ;
+
+    private String emoji;
+    CommandCategory(String emoji)
+    {
+        this.emoji = emoji;
+    }
+
+    public String getEmoji() { return emoji; }
+}

src/main/java/wtf/beatrice/hidekobot/objects/commands/MessageCommand.java

@@ -39,6 +39,13 @@ public interface MessageCommand
      */
     boolean passRawArgs();
 
+    /**
+     * Say what category this command belongs to.
+     *
+     * @return the command category.
+     */
+    CommandCategory getCategory();
+
     /**
      * Run the command logic by parsing the event and replying accordingly.
      *