Page fetch tool with multiple strategies

[fortuna]

I added support for dialing over SOCKS5 and packet splitting and created a page fetch tool that gets a page using the transport specified in the command line: #45

Direct fetch:

$ go run ./x/outline-fetch/main.go https://ipinfo.io
{
  ...
  "city": "Amsterdam",
  "region": "North Holland",
  "country": "NL",
  ...
}                                  

Using a Shadowsocks server:

$ go run ./x/outline-fetch/main.go -transport ss://[redacted]@[redacted]:80 https://ipinfo.io
{
  ...
  "region": "New Jersey",
  "country": "US",
  "org": "AS14061 DigitalOcean, LLC",
  ...
}

Using a SOCKS5 server:

$ go run ./x/outline-fetch/main.go -transport socks5://[redacted]:5703 https://ipinfo.io
{
  ... 
  "city": "Berlin",
  "region": "Berlin",
  "country": "DE",
  ...
}

Using packet splitting:

$ go run ./x/outline-fetch/main.go -transport split://3  https://ipinfo.io
{
  ...
  "city": "Amsterdam",
  "region": "North Holland",
  "country": "NL",
  ...
}                                  

You should see this on Wireshark: