Add new MRTs for the HOPS survey

Add new machine-readable tables in ancillary/ for the HOPS (NH_3) survey.
Slightly adjust d_tan assignment

Slightly fudge the "T" assignment to w/in 1.05 kpc of d_tan instead of 1.00 kpc.
This is close enough to before, but was needed to catch a couple errant sources
that really should be at the tangent point but weren't with the 1.00 limit.
Adjust the normalized 3-D association distance \xi

Adjust the computation of the normalized 3-D association distance for in
dpdf/prob_hrds.pro and dpdf/prob_parallax.pro to be sqrt(d^2 + v^4) based on
the turbulent structure function (thanks, Erik!).