outputs optimization to file. fixed by flushing and closing output stream appropriately.
Add return code strings for BFGS optimizer.
BFGS parameter changes.  Add tol_obj, tol_param and tol_grad parameters.  Change stepsize to init_alpha as it better reflects its use.
pulling out common code
updated return codes for bfgs optimization
Clean up BFGS code and messages a bit further.
Merge branch 'develop' into feature/issue-259
Merge branch 'develop' of https://github.com/stan-dev/stan into develop
alphabetized function_signatures.h
renaming stan::math::epsilon() to stan::math::machine_precision()
removing undoced functions from function signatures
removing commented block
Fix bug introduced in recent cleanup.
added citations, checked format
Merge branch 'develop' of https://github.com/stan-dev/stan into feature/issue-187-citations
Merge pull request #274 from stan-dev/feature/issue-248-functions

Fixes #248. remove function signatures for undoc'ed functions
Merge pull request #277 from stan-dev/feature/issue-187-citations

Fixes #187. Updated citations
Merge pull request #261 from stan-dev/feature/issue-259

Fixes #259. Optimization broken in develop (pull request)
added more print statements to makefile
added TEMPLATE_DEPTH parameter to makefile under mac only.