日志相关修改

* 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>

日志文件越来越大，原有的清空日志只是清理记录窗口中显示的日志，实际并没有真的删除。

User requested.

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

- use null conditional access in case some connections been
  cancelled unexpectedly and may cause null reference exception
- Refine error message
- use conditional operator to simplify some code

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

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

- display user-friendly server name
- clarify proxy type

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

# Conflicts:
#	shadowsocks-csharp/Controller/Service/TCPRelay.cs
#	shadowsocks-csharp/Controller/ShadowsocksController.cs
#	shadowsocks-csharp/View/MenuViewController.cs

* Drop unused variable to suppress warning in LogForm

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

* Fix IPv6 displaying

It is a little ugly, send a PR if you can find a better way.

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

Note:
- Added a configuration entry, user should add this
  by hand or reset from scratch.

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

This exception is caused by processing Invoke Action while trafficChart is already disposed.

=====
Exception reproduce frequency: RARE. Once triggered, ShadowSocks crashes.

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

* Implement the line chart on Log View window for inbound/outbound traffic per second

* Implement dynamic tray icon to indicate Inbound and Outbound

* Refine linechart

* Bugfix for dynamic icon

* Refine chart presentation

* Change the data points' type for more accurate calculation

* Tweak inbound/outbound indicator image for tray icon

"Server IP" -> "Server Addr"

Correct AvailabilityStatistics's behavior under special strategies like "LoadBalance", which may switch the server several times in a short period.

# Conflicts:
#	shadowsocks-csharp/Controller/Service/AvailabilityStatistics.cs
#	shadowsocks-csharp/Controller/Strategy/StatisticsStrategy.cs
#	shadowsocks-csharp/View/StatisticsStrategyConfigurationForm.cs

# 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>