added failing test
switched to no namespace erf in math.h
updating arithmetic in owens_t
updating arithmetic in owens_t
updating includes
updated testing framework to take in argument bool is_grad_nan
added NaN test for log_falling_factorial
added NaN test for ceil
fixed NaN tests for log_inv_logit and log_rising_factorial
added NaN test for fma
added NaN test for fmod
added NaN test for multiply_log
added NaN test for pow
added NaN test for operator_addition
add NaN test for operator_divide_equal
added NaN test for operator_division
added NaN test for operator_minus_equal
added NaN test for operator_multiplication
added NaN test for operator_multiply_equal
added NaN test for operator_plus_equal