Test converson code to/from GMP
===============================

>>> import gmpy2
>>> from gmpy2 import mpz, mpq

>>> float(mpz(1))
1.0
>>> float(mpq(1,2))
0.5
>>> float(mpz(99**199))
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
OverflowError: ** message detail varies **
>>> mpz(gmpy2.xmpz(1))
mpz(1)
