use set_alert_dispatch instead of timer to get an alerts from libtorrent

Conflicts:
	src/qtlibtorrent/qbtsession.cpp
use post_status_update()

Conflicts:
	src/qtlibtorrent/qbtsession.cpp
extract torrent statistics from torrent speed monitor to separate file
use stats_alert in TorrentSpeedMonitor

Conflicts:
	src/qtlibtorrent/qbtsession.cpp