Gosper's continued fractions for Python, using lazy evaluation.

Author:
Marcin Ciura <mciura at gmail.pl>

Web references:
* Ralph William Gosper, Continued Fractions. In: HAKMEM,
  http://home.pipeline.com/~hbaker1/hakmem/cf.html
* Ralph William Gosper, Continued Fraction Arithmetic
  http://www.tweedledum.com/rwg/cfup.htm
* Mark Jason Dominus, Arithmetic with Continued Fractions,
  http://perl.plover.com/yak/cftalk/
* Jean Vuillemin, Exact Real Computer Arithmetic with Continued Fractions
  ftp://ftp.inria.fr/INRIA/publication/publi-pdf/RR/RR-0760.pdf
* Philippe Flajolet, Brigitte Vallée, Ilan Vardi,
  Continued fractions from Euclid to the present day,
  http://citeseer.ist.psu.edu/flajolet00continued.html

Started by Marcin Ciura <mciura at gmail.pl> 01.03.2007
- supports Python 2.4 math functions

Changed by Adam Przybyla <adam@ertel.com.pl> 07.09.2011
- added Python 2.6 math compatibility functions: 
- ldexp(x,y) frexp(x) fsum(x) isnan(x) isinf(x) atanh(x) copysign(x,y) log1p(x) trunc(x) acosh(x) asinh(x) factorial(x)
- fixed NaN error

Changed by Adam Przybyla <adam.przybyla@gmail.com> 10.07.2018
- added all Python 2.7 math compatibility functions: 
- erf erfc lgamma gamma expm1
- version 0.2