Store Gelman-Rubin statistic as first entry in chain, moving best-fit
parameters to second entry in chain.
Removing extraneous debugging output.
Bugfixes to map plotting in plotmap.py, along with new measures
of reddening to plot:
  * mean
  * 5th percentile
  * 95th percentile
Changed plot numbering scheme to allow more distance slices to be saved from plotmap.py
Fixed mismatched new * and delete
Merge branch 'write-GR' into develop
Important fixes to replacement steps. Addressed segfault problem in l.o.s. integrals
No replacement steps in piecewise-linear model by default.
Use 95th percentile of ln(Z), rather than maximu, in determining
threshold for rejection.
Merge branch 'separate-step-types' into develop