Beefed  upDeltaApplicationVisitorFixture, puttered

- added series of tests to DAVF, still need to consider testing visitors
- cleaned up some using statements
- found more bugs in visitor implementation, cleaned those out. Involves
exposing something nasty through IVersionControlNode, something that
should really be internal to the class.
- put some warnings on the IVersionControlNode interface for later
investigation.
- tidied up versioning list
- pushed resharper preferences into file, will see if the propagate to
laptop.
- further moved "handy-to-have" methods from List to List extension
methods.
- played around with ICloneable, came up with something not atrocious.
Merge branch 'master' into laptop_work

Conflicts:
	VersionCommander.sln.DotSettings
	VersionCommanderTests/DeltaApplicationVisitorFixture.cs
	VersionCommanderTests/PropertyVersionControllerFixture.cs
	VersionCommanderTests/TestingAssists/TestHelper.cs
	VersionCommanderTests/TestingBasicC#Knowhow.cs
	VersioningPropertyBag/Extensions/MsCorLibExtensions.cs
	VersioningPropertyBag/Extensions/TypeExtensions.cs
	VersioningPropertyBag/IVersionControlNode.cs
	VersioningPropertyBag/NullObjects/NullVersionControlNode.cs
	VersioningPropertyBag/PropertyBagVersionController.cs
	VersioningPropertyBag/PropertyVersionDelta.cs
	VersioningPropertyBag/VersionControlNodeBase.cs
	VersioningPropertyBag/VisitorFactory.cs
	VersioningPropertyBag/Visitors/DeltaApplicationVisitor.cs
	VersioningPropertyBag/Visitors/DescendentAggregatorVisitor.cs