Improvement for DiagnosticsWindow: Types are not removed and RefCount does only increase

[lolhans]

When dynamically instancing and destroying LifetimeScopes, the Types do not get removed from the Diagnostics Window and the RefCount on Contracts does only increase.

I would rather expect a behaviour, where the Type gets removed and the RefCount (e.g., on a contract of the ProjectInstaller) decreases everytime when the Dispose() method is called on a LifetimeScope, that implements a specific ContractType.