create tool to generate addresses for manual snapshot creation

[acud]

tool should be able to generate a random address and give back the kademlia base address, enode id and private key for that address.

now when we would like to create neighbors or other peers for an arbitrary topology, the same tool should be able to take in a private key or kademlia base address and a wanted PO for the new address and then brute-force the correlating under/overlay addresses with their corresponding private keys.

example usage:

swarm-snapshot generate random
<dump 1 random address, enode, private key here>

swarm-snapshot generate --baseaddr="base address" --po=2
<dump 1 brute forced address with enode, base addr and private key here>

swarm-snapshot generate --baseaddr="base address" --po=2,4,4,7,8
<dump 5 brute forced addresses with enode, base addr and private key here>