Castメソッドを追加
Merge branch 'change-vm-prop' of https://github.com/k-maru/friendly.pininterface into k-maru-change-vm-prop

Conflicts:
	Project/Test/UsabilityTest.cs
	Project/VSHTC.Friendly.PinInterface/Inside/FriendlyProxyInstance.cs
	Project/VSHTC.Friendly.PinInterface/PinInterfaceExtensions.cs