Refactored method Hook<T>.InstallHook() to accept any InvokableHook rather than just HookDelegateListEntry<T>, to support delete hook registration.
Implemented Hook<T>.OnDelete by installing a ulong-hook and using the specified T as the triggering type rather than a signature.
Added helper methods InvokableHook.InvokeInsert, InvokeUpdate and InvokeDelete to support the Transaction class when it should invoke installed hooks.