Added NR55 to the VR109 page

Added an NR55 triode to the VR109 page. This valve is unusual in that there is evidence it had a sprayed shield which has been almost completely removed. It carries the  NR55 marking and nothing else on the glass, and the serial number 9505. The EVS data for the equivalent CV1109 indicates the valve is not sprayed. The data for CV1000 also says it is derived from NR55, and again says the valve is not spray shielded.