706 and new line dense spectral scan.

[bberkeyU]

This may get accomplished by ticket #7, but we should perform some dense scans of our weak/missing lines to try and understand the tuning.

For 706, in particular, the prefilter was designed around the vacuum wavelength, so we may need to move the prefilter and add extra tilt to center it. The continuum spectra are hard to explain, as the assumed HeI signal appears in the wrong wavelength channel.