Support more transports, encryption methods

[Kief]

Original issue

Some customization towards connection would be nice and its a standerd between most vpn clients.

Perhaps:

• Connection type (tcp, other types)
• Encryption (some work better then others)
• Don't use vpn for forign websites (for example bing.com can be accessed in China)
• More features that improve QOL and more reliability for connections

[Baiyi Liao]

This I can answer!

1. About Connection Type: TOSS outline-server out of the window! Use server implementations like shadowsocks-rust instead to unlock full potential of Outline. If you are asking about "what about using TCP only and not forwarding UDP" ("我想只转发TCP流量，UDP直连可以吗“), I've asked about this in #467 years ago and Outline will work without UDP relay just fine, given that you do NOT enable UDP relay on the server side.

2. About Ciphers ("加密", "算法"): AEAD ciphers like chacha20-ietf-poly1305 and the AES-GCM-xxx works with Outline, and there is actually no point doing fancy stuff over it because it's SOCK5 anyway...The topic of one cipher being faster than another was about chacha20 beating AES in the python server days. Today, we have C / Rust powered server implementations and our clients most likely have hardware acceleration for both chacha20 and AES. Not a relevant question. With that said, using a vanilla shadowsocks server will give you the ability to use ciphers other than chacha20-ietf-poly1305, just be aware that none-AEAD ciphers are NOT secure as suggested on the SIP022 document from Shadowsocks.org.

3. domain / IP bypass by rule: Nope, not worthwhile as this software's goal is not about having a smooth experience in some country blocking some websites. see #887.

4. What do you mean by QOL(Quality-Of-Life) features? If you mean something like obfuscation, then nope, will not support it as well. See #649

With that said, please feel free to fork this repo and implement the feature you like! Let us know!