btrtrc -- better BitTorrent client

This is a fork of https://github.com/anacrolix/torrent BitTorrent
library with own cmd/btrtrc client implementation. Comparing to
cmd/torrent it has much less configuration options, mainly hardcoding
the most of them. But what advantages does it have, not including its native
capabilities (IPv6, DHT, μTP, PEX, magnet links, HTTP/UDP trackers)?

* Optimized file-based storage:
  * linearized I/O operations prevent creation of huge quantity of threads
  * cached file descriptors save a lot of syscalls
* Shortened long filenames in file-based storage
* Ability to specify both IPv4 and IPv6 addresses to announce
* Ability to specify DHT bootstrap nodes
* Dynamic addition and removing of the torrents
* Much richer and nicer coloured status output
* Ability to calculate seed ratio, by remembering outgoing traffic amount
* Simpler piece completion database per each torrent in separate files
* Ability to sequentially create/verify torrent's piece completion database

Look at USAGE file further.

btrtrc is free software: see the file LICENSE in the root of the
repository for copying conditions.