Renamed solution file to match the project name.
Used IXCollection almost everywhere in XCache.
Removed an option to call non-public constructors within the Activator.CreateInstance.
Improved code contracts.
Replaced the Updated event with a PropertyChanged equivalent.
Merge branch 'remove-updated-event' into dev
Introduced "sorted collection".

Working DCL-11 : Требуются коллекции, поддерживающие сортировку/фильтрацию в реальном времени
Refactoring.

BeginUpdate/EndUpdate do not lock updating of base collections.
Merge branch 'DCL-11' into dev
Removed redundant code contracts assumptions.
SetProperty: replaced Equals check with the ReferenceEquals one.
Version bumped to 4.1.
XKeySerializer moved to Digillect.Runtime.Serialization namespace
XParameters class reimplemented as an almost-full copy of XKey. XParametersSerializer added as well.
Used CallerMemberNameAttribute for property names within .NET 4 based targets (thanks to the BCL Portability Pack).
Merge branch 'ms.bcl-dependency' into dev
Used private xUnit runner from NuGet package.

Code contracts support stuff moved to a separate .targets file.
Added method XParameters.GetValue that supports default value.
Modified behavior of XParameters.GetValue to return default value if name is not found.
Added XParameters.Contains method.
Modified the Test target to use a special xunit MSBuild task rather than a standalone console executable.
Release 4.1.0.