moving src/stan/agrad/error_handling.hpp to boost_fpclassify.hpp
moving old_error_handling_test.cpp back
updating test/agrad/error_handling_test
splitting out check_not_nan tests from agrad/error_handling
splitting out check_not_nan tests from agrad/error_handling
splitting out check_bounded tests from agrad/error_handling
removing unused test
splitting acosh out of agrad/special_functions.hpp
splitting asinh out of agrad/special_functions.hpp
splitting atanh out of agrad/special_functions.hpp
splitting atanh out of agrad/special_functions.hpp
splitting atanh out of agrad/special_functions.hpp
splitting erfc out of agrad/special_functions.hpp
splitting exp2 out of agrad/special_functions.hpp
splitting expm1 out of agrad/special_functions.hpp
splitting log1p out of agrad/special_functions.hpp
splitting log1m out of agrad/special_functions.hpp
splitting log1m out of agrad/special_functions.hpp
splitting fma out of agrad/special_functions.hpp
splitting fma out of agrad/special_functions.hpp