Lock is evil.

This will actually affect the accuracy of GetDelta because
inboundDelta and outboundDelta may be calculated based on
the data collected at different time (eg. UpdateOutbound
get called before Interlocked.Read(ref _outbound)).

But that's not a problem. We can tolerate this little
inaccuracy. Besides, the _inbound, _outbound, _lastInbound
and _lastOutbound will be totally good because we use Interlocked.

Use lock to sync between threads.This should fix issue #679
and other same issue.

Fix a bug in UpdateSpeed() that only save the first xxxSpeedRecord.

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>

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

prevent a bug

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

# Conflicts:
#	shadowsocks-csharp/Controller/Service/AvailabilityStatistics.cs

# Conflicts:
#	shadowsocks-csharp/Controller/Service/AvailabilityStatistics.cs
#	shadowsocks-csharp/Controller/Strategy/StatisticsStrategy.cs
#	shadowsocks-csharp/View/LogForm.Designer.cs
#	shadowsocks-csharp/View/MenuViewController.cs

Strategy: Simply Choose By Statistics