- Extended the method Number.is_pow() to accept an optional argument for power.
- Extended the method Number.is_pow() to accept an optional argument for power.

Example:
	100.is_pow(2)		# true: 100 is square (10**2)
	125.is_pow(3)		# true: 125 is a cube ( 5**3)

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