Merge branch 'develop' of https://github.com/stan-dev/stan into bugfix/issue-593-op-short-circuit
Merge branch 'develop' of https://github.com/stan-dev/stan into develop
Merge branch 'develop' into bugfix/issue-593-op-short-circuit
adds short-circuit for logical binary ops, with primitive_value support template function
added doc for short circuiting
Merge pull request #1048 from stan-dev/bugfix/issue-593-op-short-circuit

Fixes #593. Bugfix/issue 593 op short circuit