slightly faster zero check in Secant. add missing 'bisect' to findroot docstring
slightly faster zero check in Secant. add missing 'bisect' to findroot docstring

bjodah/mpmath,JensGrabner/mpmath,bjodah/mpmath,fredrik-johansson/mpmath,JensGrabner/mpmath,klkuhlm/mpmath,klkuhlm/mpmath