Merge branch 'develop' of https://github.com/stan-dev/stan into develop
fixed and tested conversion routing array indexing ltr_2_rtl (row-major to column major)
Merge pull request #627 from stan-dev/bugfix/issue-624-json-compare-unsigned

Fixes #624. Bugfix/issue 624 json compare unsigned
Merge branch 'develop' of https://github.com/stan-dev/stan into feature/issue-597-function-lang