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!).
Add parallax parser routine

Routine parses the Table 1 of Reid et al. (2014) of parallax data for 103
sources across the Galactic plane.  That table is listed in celestial (RA,Dec)
coordinates (honestly, when dealing with Galactic plane stuff, WHY??!?), and
this routine computes (l,b), as well as saves the table into an IDL save file.
Add distance tables from Dunham et al. (2011b)

New MRTs in the ancillary/ directory for distances derived in conjunction with
ammonia observations of molecular cloud structures.
Changed column label in ancillary/Dunham_2011b_table6.mrt

ApJ likes to have E_ and e_ represent the upper and lower error bars on a
measurement, when unequal.  However, in case-insensitive languages (like IDL)
this causes much pukage.  The columns have been renamed as p_ and m_ for
plus- and minus-error-bars.
Merge branch 'master' into release

Merge latest version of the master branch into 'release' before sending a pull
request to the main repo.  This will be a test for tagging, as well.