* Track upload and download data.
 * Emulate a UDP server in the UDP tracker tests.
 * Make use of sparse file regions in download data for faster hashing.
 * If we're choked and interested, we never send not-interested if there's nothing we want?
 * Don't announce torrents that don't need active peers. It spams UDP, fills memory, and publicizes what we have loaded.
 * Randomize triedAddrs bloom filter to allow different Addr sets on each Announce.