Errors when using embedded transforms in vtkPlusOpenIGTLinkVideoSource

[Sunderlandkyl]

• If the From and To coordinate frames of the embedded transform are the same, the Transform repository will log an error ("Setting a transform to itself is not allowed") when sending any images using vtkPlusOpenIGTLinkServer.
• If an incoming image message has no status set for the embedded transform, the transform is considered invalid.
• When connecting to another PlusServer, no data will be received by vtkPlusOpenIGTLinkVideoSource if ImageMessageEmbeddedTransformName is not specified.

See discussion here: #871