Extending to_string To Another Floating Point Type

Base Requirement
If the function to_string is used by an AD type above Base , A specialization for the template structure CppAD::to_string_struct must be defined.

For most Base types, the following can be used to define the specialization:       namespace CppAD {           CPPAD_TO_STRING(Base)      }  Note that the CPPAD_TO_STRING macro assumes that the base_limits and base_std_math have already been defined for this type. This macro is defined as follows:
# define CPPAD_TO_STRING(Base) \
};