Added optional prior that dust density roughly traces stellar disk.
Using 10x SFD to normalize disk-like dust prior.
Loosening log(E(B-V)) prior to sigma=10.
Using chi^2 distribution for disk-like dust density (k=2)
Reverting to Gaussian distribution for disk-like dust density, and adding factor of log(EBV) to ln(p).
Widening E(B-V) Gaussian
Merge branch 'galactic-EBV-priors' into develop