automatic detector of common APT proxy settings

 auto-apt-proxy installs itself as an APT proxy autodetector, and detects
 common setups by checking some hosts on the local network for well-known APT
 proxies such as apt-cacher-ng.
 .
 This package is most useful for development environments, and will Do The
 Right Thing for at least these cases:
 .
   * Build chroots, with a proxy running on the host system.
   * Docker/lxc containers, with a proxy running on the host system.
   * Virtual machines with NAT networking, with a proxy running on the host
     system.
   * Any other system, with a proxy running on its default gateway.
   * Systems where the `apt-proxy` hostname resolves to a valid IP address
     and a supported proxy is detected at that address.
 .
 The following APT proxy servers are supported and automatically detected:
   * apt-cacher-ng
   * approx
   * apt-cacher
   * squid-deb-proxy
   * any proxy advertised by an _apt_proxy._tcp SRV record in your domain
 .
 This package has a minimal set of dependencies in order to minimize the
 influence on systems where it is installed.
 .
 This package does not query mDNS SRV records, which would require avahi.
 If you need that, consider the `squid-deb-proxy-client` package instead.