Add netblocks

[HerrSpace]

Plugins might bring in a bunch of secondary services like ADs/Facebook/AWS ranges.. I'd like a way to auto (no)scope targets based on ip ranges.

Done:

• Add ipnet model and boilerplate
• Add cli support for ipnets

Todo:

• Inherit scope of new ipaddrs from smallest enclosing ipnet
• support recursively (no)scoping ipaddrs in networks
• Add default ::/0 and 0.0.0.0/0 nets
• Come up with what the cli stuff should look like

[HerrSpace]

@kpcyrd I'll hand this over to you then, alright?

[kpcyrd]

@HerrSpace sure, thanks a lot for your contribution! :)