Help: In debug mode, show unit type id's in their help topics.

Useful when multiple unit types have the same name.

src/help/help_impl.cpp

@@ -950,7 +950,8 @@ std::vector<topic> generate_unit_topics(const bool sort_generated, const std::st
 		if (desc_type != FULL_DESCRIPTION)
 			continue;
 
-		const std::string type_name = type.type_name();
+		const std::string debug_suffix = (game_config::debug ? " (" + type.id() + ")" : "");
+		const std::string type_name = type.type_name() + (!strcmp(type.id().c_str(), type.type_name().c_str()) ? "" : debug_suffix);
 		const std::string real_prefix = type.show_variations_in_help() ? ".." : "";
 		const std::string ref_id = hidden_symbol(type.hide_help()) + real_prefix + unit_prefix +  type.id();
 		topic unit_topic(type_name, ref_id, "");