- Fixed the MPFR rounding in next_pow2() and next_pow().
- Fixed the MPFR rounding in next_pow2() and next_pow().

Example:

	say (next_pow(3**12345, 3) == 3**12345)		#=> true (before was false)

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