hopefully ready to release rstan 2.17.2

makeconf_path(): try to generalize it

prepare to release 2.15.1

DESCRIPTION: bump version number

NEWS for 2.14.x

external.Rmd: discuss auto and decltype

rtools.R: eliminate old code

NEWS: amend for 2.11.1

fix vignettes to hide output and not use cache

change strategy for dealing with SPARC