nirex updates
added essential nirex dependency
add an in-out tool for extinction mapping
GRS 13CO velocity matching successful.

13CO - HCO+ velocity matching is at 95% for the entire BGPS-GRS overlap,
including 13CO with multiple peaks.  13CO On-Off must have Ta >= 0.3 K, and
multiple-velocity components must have a T_primary / T_secondary >= 1.5
ratio.  This commit includes the testing code (idl/view_grs_l30.pro) as well
as many plots.

These criteria will be incorportated into the distance-omnibus IDL code base.
Merge branch 'master' of github.com:keflavich/distance_omnibus2

Add Adam's recent work on the repo into my own copy.