fixed SynchronizedHashtable
SPRNET-974: support private ctors with ConstructorNode
SPRNET-975: treat alias case insensitive as well
SPRNET-976: defered registering WebObjectFactory event handlers with VirtualEnvironment to when they are really needed
SPRNET-977: avoid unnecessary usages of HttpContextSwitch in WebObjectFactory.ConfigureObject()
added tests
added VirtualEnvironment HttpSessionState/HttpRequest abstraction
