This PR merges webtorrent-tracker into this repo. Keeping the code in
sync between the two repos was becoming burdensome. This change should
not effect performance of the server since the webtorrent tracker is
disabled by default.
To enable the webtorrent tracker (disabled by default), do:
```js
var server = new Server({ ws: true })
```
Breaking changes:
- 'listening' event no longer emits with `port` param
- `server.port` property removed (instead, use
`server.http.address().port`)
Added features:
- expose http server as `server.http`
- expose udp server as `server.udp`
- client.destroy() - ungracefully leave the swarm
- server: added `filter` option to black/whitelist torrents
Bugfixes:
- client considers udp tracker errors to be warnings
- emit 'start', 'stop', 'update', etc. AFTER response sent
- fix udp error response action and message being `undefined`
Internal:
- remove `portfinder` dep
- add complete test for `filter` functionality
