Handle announce URLs with parameters correctly

- Disable KRPC
- Shorten tracker string

- Better BEValue.toString()

(most of the following got missed in the last checkin)
- Fix about 9 NPEs
- Fix numwant in magnet mode
- Send metadata size in extension handshake
- Open trackers are primary if we don't have primary trackers
- Add missing break in port message handling
- Increase max msg size to account for metadata msg
- Remember magnets across restarts
- Drop peers w/o extensions if we need metainfo
- Fix DATA messages
- Fix tracker transition to non-magnet
- Fix infohash for non-magnet
- Fix up peer transition to non-magnet
- More logging

- Record the metadata bandwidth
- More null announce handling
- Callbacks for got MetaInfo event
- Cleanups