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

NEWS: update for 2.9.0

update NEWS

Merge branch 'develop' of https://github.com/stan-dev/rstan into develop

DESCRIPTION: bump date

bump Date in DESCRIPTION

single-quote 'StanHeaders'