DOC: remove links to crate.io
DOC: Add discussion of how to avoid recompiling stan models.
Allow disabling multiprocessing via JOBLIB_MULTIPROCESSING=0
Update version
Add tox.ini to facilitate testing

It is worth noting that travis-ci does not test parallel sampling (tests are not
allowed to query the number of processors available). For this reason it seems
worthwhile to run tests locally on occasion by just typing ``tox``.
BLD: Install libstan.a to pystan/ for simplicity
DOC: Mirror docs improvements from RStan
DEV: Update C++ wrapping for Stan 2.1.0
TST: Add tests for new sampler parameters in Stan v2.1.0
Squashed 'pystan/stan/' changes from 0dc2d86..fad1ae2


git-subtree-dir: pystan/stan
git-subtree-split: fad1ae230db500dc214bf070357ce838225a9ea5
Update Stan source to tag v2.1.0

Merge commit '4c986e428b3a5cf9da85cb458e2cb6f7b7008038' into develop