- 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>

- 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

I can't wait until PR #604 get merged, do it manually.

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>

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

Squashed commit of the following:

commit e280c2385c
Merge: 579039f 87aa9eb
Author: Gang Zhuo <gang.zhuo@gmail.com>
Date:   Wed Mar 16 04:02:27 2016 -0400

    Merge remote-tracking branch 'origin/master'

commit 579039fe40
Author: Gang Zhuo <gang.zhuo@gmail.com>
Date:   Fri Mar 4 21:45:23 2016 +0800

    log unhandle exception

commit 8d863f1d5f
Author: Gang Zhuo <gang.zhuo@gmail.com>
Date:   Fri Mar 4 21:44:54 2016 +0800

    fix Availability Statistics

commit b3ce1c698a
Author: Gang Zhuo <gang.zhuo@gmail.com>
Date:   Fri Mar 4 21:07:54 2016 +0800

    tiny refactor

commit 0f7d39e27e
Merge: bd7078a b01aced
Author: Gang Zhuo <gang.zhuo@gmail.com>
Date:   Fri Mar 4 20:02:58 2016 +0800

    Merge remote-tracking branch 'origin/master'

commit bd7078aa4f
Author: Gang Zhuo <gang.zhuo@gmail.com>
Date:   Fri Mar 4 20:01:58 2016 +0800

    tiny refactor

commit 49adb95b6e
Author: Gang Zhuo <gang.zhuo@gmail.com>
Date:   Fri Mar 4 03:44:26 2016 -0500

    log more Ping information for debug

commit 2aa0620ddd
Author: Gang Zhuo <gang.zhuo@gmail.com>
Date:   Fri Mar 4 03:04:10 2016 -0500

    reduce 3rd packages

[solve conflicts and squash to make history clean]
Signed-off-by: Syrone Wong <wong.syrone@gmail.com>

Replaced SocketFlags.None (an enum which euqals 0) from zero.

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

https://msdn.microsoft.com/library/ms182172.aspx

# 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