MP Lobby: highlight the titles of MP games with vacant slots

(cherry-picked from commit 3e27ccaf18)

changelog.md

@@ -62,6 +62,7 @@
    * Added a convenient button in Load Game to open your saves folder.
    * Fixed context menus not dismissing on right click.
    * Removed individual Join/Observe buttons for each game in the MP Lobby.
+   * Highlight the titles of MP games with vacant slots.
  ### WML engine
    * Support formula= key in [variable] ConditionalWML
    * Support to_location in [move_unit], taking a location ID

src/gui/dialogs/multiplayer/lobby.cpp

@@ -423,7 +423,7 @@ std::map<std::string, string_map> mp_lobby::make_game_row_data(const mp::game_in
 		color_string = (game.reloaded || game.started) ? font::YELLOW_COLOR : font::GOOD_COLOR;
 	}
 
-	item["label"] = game.name;
+	item["label"] = game.vacant_slots > 0 ? colorize(game.name, font::GOOD_COLOR) : game.name;
 	data.emplace("name", item);
 
 	item["label"] = colorize("<i>" + game.scenario + "</i>", font::GRAY_COLOR);