Update vrpn_Tracker_NDI_Polaris.C

[EvanKrueger]

I'm hoping this patch from our contact at NDI will fix the tracking of rigid bodies when using VRPN with the NDI Polaris Spectra device. I've included his comments below.
Original file: simple_vrpn.cpp.txt

One thing I did notice is that the 'IRATE 0' command is used in 'vrpn_Tracker_NDI_Polaris.C'
The IRATE command is deprecated for the SET command. The default illuminator rate is 20 Hz, so to set the illuminators to 60Hz the command should be:
SET PS-0.Param.Illuminator Rate=2

I also found the parsing function 'parse7CharFloatFromNDIResponse' returned the incorrect values. Looks like it was due to data type conversion, but in any case I wrote a simple file with some modifications. With these modifications I got better results. I have not been able to test it fully, or add it into the VRPN project as of yet. I've attached the project files, let me know if you can run it with better results.

Regards,
Ryan