No error_code overload for the lt::load_torrent_* functions

[dodicidodici]

Currently, the load_torrent_file, load_torrent_parsed, and load_torrent_buffer functions do not have an overload w/ lt::error_code.

libtorrent/src/load_torrent.cpp

Lines 122 to 144 in 44598ba

	add_torrent_params load_torrent_file(std::string const& filename, load_torrent_limits const& cfg)
	{
	add_torrent_params ret;
	ret.ti = std::make_shared<torrent_info>(filename, cfg);
	update_atp(ret);
	return ret;
	}
	add_torrent_params load_torrent_buffer(span<char const> buffer, load_torrent_limits const& cfg)
	{
	add_torrent_params ret;
	ret.ti = std::make_shared<torrent_info>(buffer, cfg, from_span);
	update_atp(ret);
	return ret;
	}
	add_torrent_params load_torrent_parsed(bdecode_node const& torrent_file, load_torrent_limits const& cfg)
	{
	add_torrent_params ret;
	ret.ti = std::make_shared<torrent_info>(torrent_file, cfg);
	update_atp(ret);
	return ret;
	}

The functions make use of the lt::torrent_info constructor, specifically the non-lt::error_code overload, which isn't available when building without support for exceptions.

[arvidn]

would you expect such overloads to return an optional<add_torrent_params>?