sync with shadowsocks-libev

Signed-off-by: Syrone Wong <wong.syrone@gmail.com>

- Create instance once, bind it to ShadowsocksController

Signed-off-by: Syrone Wong <wong.syrone@gmail.com>

Signed-off-by: Syrone Wong <wong.syrone@gmail.com>

Signed-off-by: Syrone Wong <wong.syrone@gmail.com>

- Use separate encrypt/decrypt buffer when creating instances
- Revert 3bc77d212a

- Use readonly object as lock

Info from stackoverflow:

If I want to be sure that it will be locked for all threads inside my
application:
The lock object has to be static, if it locks access to static state.
Otherwise it has to be instance, because there's no need to lock state of
one class instance, and prevent other threads to work with another class
instance at the same time.

everyone says that the object has to be "readonly" I didn't found the
reason
Well, it doesn't have to be. This is just a best practice, which helps you
to avoid errors.

Signed-off-by: Syrone Wong <wong.syrone@gmail.com>

introduce a constructor to store inner method name

Signed-off-by: Syrone Wong <wong.syrone@gmail.com>

- use EncryptorInfo struct instead of Dictionary<string, int[]>>

and misc changes

Signed-off-by: Syrone Wong <wong.syrone@gmail.com>

- drop unused using directive
- add a comment

Signed-off-by: Syrone Wong <wong.syrone@gmail.com>

- Drop redundant code.
  I should read code carefully, mbed TLS will set operation
  when invoking mbedtls_cipher_setkey(), the last param
  const mbedtls_operation_t operation is what we want.
- minor changes

Signed-off-by: Syrone Wong <wong.syrone@gmail.com>

* Refine encryption

- Add AES-CTR, blowfish and camellia ciphers

aes-256-ctr
aes-192-ctr
aes-128-ctr
bf-cfb
camellia-128-cfb
camellia-192-cfb
camellia-256-cfb

- Merge the previous PolarSSL and MbedTLS
- Switch to MbedTLS's cipher layer functions
- Add workaround to set cipher operation(encrypt/decrypt)

Signed-off-by: Syrone Wong <wong.syrone@gmail.com>

* Add function to get MbedTLS cipher context size

and drop hard-coded ctx sizes

Signed-off-by: Syrone Wong <wong.syrone@gmail.com>

- use mbedtls_md5() instead
- update libsscrypto

Signed-off-by: Syrone Wong <wong.syrone@gmail.com>

# Conflicts:
#	README.md
#	shadowsocks-csharp/Controller/Service/AvailabilityStatistics.cs
#	shadowsocks-csharp/Controller/Service/PACServer.cs
#	shadowsocks-csharp/Controller/Strategy/SimplyChooseByStatisticsStrategy.cs
#	shadowsocks-csharp/Data/cn.txt
#	shadowsocks-csharp/Model/Configuration.cs
#	shadowsocks-csharp/Model/LogViewerConfig.cs
#	shadowsocks-csharp/View/LogForm.Designer.cs
#	shadowsocks-csharp/View/LogForm.cs
#	shadowsocks-csharp/View/MenuViewController.cs

ChaCha20 with an extended (96 bit) nonce and a 32-bit counter has
been implemented as crypto_stream_chacha20_ietf() from LibSodium 1.0.4

Please refer to https://tools.ietf.org/html/rfc7539 for details.

Signed-off-by: Syrone Wong <wong.syrone@gmail.com>

follow with 5ae4df94e4

The stock code use class Random to generate IV, the Random is pseudo random number generator. The IV maybe repeat, this will cause shadowsocks-libev closed the sockets with the error message 'invalid password or cipher'. Reference https://github.com/shadowsocks/shadowsocks-libev/issues/389

Solution is use class RNGCryptoServiceProvider to generate IV, of course it's lower performance, but a little bit.

1. Add Logging.Info()
2. Console.WriteLine() -> Logging.Info()
3. Console.WriteLine() in exceptions -> Logging.LogUsefulException()

1/ removed dual empty line
2/ removed tailing spaces
3/ converted tabs into spaces
4/ added some TODO comments