fix how radius is computed

[tomr-stargazer]

In Rosolowsky et al. 2008, there is an "eta" factor

"We define a factor eta that relates the one-dimensional rms size, sigma r , to the radius of a spherical cloud R: R = eta sigma r. We take eta = 1.91 for consistency with Solomon et al. (1987) and Rosolowsky & Leroy (2006); the value of 1.91 merely reflects the correction of the moment to the radius for the typical concentration of emission found in molecular clouds."

I am not using this in my code, and I should be; what's more, I have been using eta in my calculation of virial alpha, so the virial alphas have been wrong by about this factor for quite some time.

I should fix this!

[tomr-stargazer]

Important: this would affect the size-linewidth fits that I have been making in the second quadrant that are directly used for the KDA disambiguation in the inner Galaxy, so I need to be careful about updating those fit parameters when I update how the size is computed!

[tomr-stargazer]

Only thing missing is including this in the new size-linewidth things.

[tomr-stargazer]

I created distance_disambiguate.py whose default fitting values come from the new eta-scaled radii from the second quadrant; now both the 1st and 4th quadrants are using the distance_disambiguator that has the eta-scaled second quadrant fit rolled in. So we can close this!