made the number of peers requested from trackers customizable

include/libtorrent/session_settings.hpp

@@ -106,6 +106,7 @@ namespace libtorrent
 			, lazy_bitfields(true)
 			, inactivity_timeout(600)
 			, unchoke_interval(20)
+			, num_want(200)
 #ifndef TORRENT_DISABLE_DHT
 			, use_dht_as_fallback(true)
 #endif
@@ -242,6 +243,9 @@ namespace libtorrent
 		// tracker in the ip= parameter.
 		address announce_ip;
 
+		// the num want sent to trackers
+		int num_want;
+
 #ifndef TORRENT_DISABLE_DHT
 		// while this is true, the dht will note be used unless the
 		// tracker is online

src/torrent.cpp

@@ -1352,7 +1352,7 @@ namespace libtorrent
 		if (m_event != tracker_request::stopped)
 			m_event = tracker_request::none;
 		req.url = m_trackers[m_currently_trying_tracker].url;
-		req.num_want = 50;
+		req.num_want = m_settings.num_want;
 		// if we are aborting. we don't want any new peers
 		if (req.event == tracker_request::stopped)
 			req.num_want = 0;