FCPPluginClient.constructForUnitTest(): JavaDoc how to create a non-fake
FCPluginClient in unit tests

- Tell the user how you can create a real Node in unit tests, and load
plugins into it as if they were loaded into a regular node. Then all
FCPPluginClientStuff likely will work like in a real node.
- Notice: I have not actually tested this yet, but will test it in WOT.