- Minor tweaks in the Number.as_cfrac() method.
- Minor tweaks in the Number.as_cfrac() method.

It will now auto-convert each MPFR value to a GMPz (if possible), allowing the "convergents()" method to return exact fractions, rather than floating-point approximations.

Example:

	say Num.pi.as_cfrac(10) 	#=> [3, 7, 15, 1, 292, 1, 1, 1, 2, 1]
	say say Num.pi.convergents(5)	#=> [3, 22/7, 333/106, 355/113, 103993/33102]

trizen/sidef,trizen/sidef,trizen/sidef,trizen/sidef