Add is private/public method

[mhf-ir]

Add is private method:

ip:isPrivate("127.0.0.1")
ip:isPrivateV4("127.0.0.1")
ip:isPrivateV6("fd12:3456:789a:1::1")

ip:isPublic("8.8.8.8")
ip:isPublicV4("8.8.8.8")
ip:isPublicV6("2400:cb00::/32")

https://en.wikipedia.org/wiki/Private_network

RFC1918 name	IP address range	Number of addresses	Largest CIDR block (subnet mask)	Host ID size	Mask bits	Classful description
24-bit block	10.0.0.0 – 10.255.255.255	16777216	10.0.0.0/8 (255.0.0.0)	24 bits	8 bits	single class A network
20-bit block	172.16.0.0 – 172.31.255.255	1048576	172.16.0.0/12 (255.240.0.0)	20 bits	12 bits	16 contiguous class B networks
16-bit block	192.168.0.0 – 192.168.255.255	65536	192.168.0.0/16 (255.255.0.0)	16 bits	16 bits	256 contiguous class C networks

[membphis]

PR welcome