LogReceiverWebServiceTarget - Dispose IWcfLogReceiverClient instead of Close

[snakefoot]

Avoid leaking WCF-clients from dangling event-handlers with references to NLog LogReceiverWebServiceTarget.

Little surprised that by default then a new WCF-client is created for every LogEvent. Would have expected that it would be more optimal to reuse the WCF-client. It is possible to inherit from LogReceiverWebServiceTarget and change the behavior to reuse the same WCF-client, but one have to implement some funny logic to avoid constant re-subscription to ProcessLogMessagesCompleted-EventHandler.

• But there is builtin a small optimization, so new LogEvents that arrives while waiting for first LogEvent to be sent, are queued and send in a single batch when first LogEvent send-completes.

Seems it is a good idea to explicit setup a NLog BufferingWrapper around LogReceiverWebServiceTarget with FlushTimeout of 200ms (or higher) to avoid constantly allocating new WCF-clients.