 fix for i73
 fix for i73

 + Make conversion from int to packed a public function.

 this allows a user to easily construct network objects from
 integers. Eg:

 >>> addr # int(ipaddr.IPAddress('1.1.1.1'))
 16843009
 >>> ipaddr.IPNetwork('%s/24' % socket.inet_ntoa(
       ipaddr.v4_int_to_packed(addr)))
 IPv4Network('1.1.1.1/24')

   Or

 >>> addr # int(ipaddr.IPAddress('2001::1')
 42540488161975842760550356425300246529L
 >>> ipaddr.IPNetwork('%s/96' % socket.inet_ntop(
       socket.AF_INET6, ipaddr.v6_int_to_packed(addr)))
 IPv6Network('2001::1/96')

git-svn-id: 47ea1648b537354ea000dbdc81f6c548b4e87acd@198 09200d28-7f98-11dd-ad27-0f66e57d2035

google/ipaddr-py,nouiz/fredericbastien-ipaddr-py-speed-up,objectsoul/ipaddr-py,objectsoul/ipaddr-py,nouiz/fredericbastien-ipaddr-py-speed-up