Feature/0568 fwd core tests

[bob-carpenter]

Submission Checklist

• Run unit tests: ./runTests.py test/unit
• Run cpplint: make cpplint
• Declare copyright holder and open-source license: see below

Summary:

Finishes testing for core C++ library component of mixed-mode autodiff up to 3rd order.

Required additions of logical operators (!, && and ||).

Tests switched from big enumerations to framework that tests against double results and tests derivatives with finite diffs.

Intended Effect:

Enable us to trust higher-order autodiff for core C++ lib.

How to Verify:

Lots and lots of tests.

Side Effects:

No.

Documentation:

Added doxygen doc for functions that didn't have it and for new functions.

Reviewer Suggestions:

anyone

Copyright and Licensing

Please list the copyright holder for the work you are submitting (this will be you or your assignee, such as a university or company):

Columbia University

By submitting this pull request, the copyright holder is agreeing to license the submitted work under the following licenses:

• Code: BSD 3-clause (https://opensource.org/licenses/BSD-3-Clause)
• Documentation: CC-BY 4.0 (https://creativecommons.org/licenses/by/4.0/)

[bob-carpenter]

Even with six new function implementations, doc for all the operators, and much more thorough testing, it's still -3000 lines!

[mitzimorris]

awesome cleanup!!!