add official way to dump network tracing info

just uncomment the specific node in app.config, no need to recompile
to take effect. It will be shipped as Shadowsocks.exe.config after built.

This is for debugging only.

add xchacha20-ietf-poly1305

- update mbedtls to 2.7.0, use new md5 api
- update libsodium to 1.0.16
- static link to openssl 1.1.0g, check libsscrypto repo for detail

Add new requirement

Add OpenSSL 1.1.0g support due to hardware acceleration

Don't use Cname

Note: If you want to compile it by yourself, please make sure
do NOT use `no-asm` configure option, since the main point of
this commit is to utilize assembly in openssl

Add OpenSSL test

SIP003 server port validation
Year 2018

Close sockets before stop plugins

Do not activate all servers' plugins at the same time

When saving user-rule.txt file, some text editors can raise FileSystemWatcher event twice.
The 1st time is blank content, then the 2nd time is the modified content.

Put user rules at the begin of the PAC file.

Close connection if received zero bytes

This might fix 500 Privoxy Internal Error: no-server-data

Fix: #1468
Enhance: 46d40fec67

Add option to show password

Sip002 refine

- Bring back the legacy parser
- Refine SIP002 logic

Base64 code ended with '=' cause the Uri invalid to parse.
Simplified the logic.

Use job objects with SIP003 plugin to avoid lingering processes if app is killed

SIP002 and SIP003 support.