FCPInterface.handleGetScores(): Remove obsolete JavaDoc

The parameter isn't allowed to be null anymore -
FCPPluginMessage.constructSuccessReply() will throw NPE if it is.
FCPInterface.handleGetTrusts(): Remove obsolete JavaDoc

The parameter isn't allowed to be null anymore -
FCPPluginMessage.constructSuccessReply() will throw NPE if it is.
FCPInterface.handleGetIdentities(): Remove obsolete JavaDoc

The parameter isn't allowed to be null anymore -
FCPPluginMessage.constructSuccessReply() will throw NPE if it is.