Tezos: library for a pool of P2P connections

add t peer adds peer to the peer greylist. It might potentially evict the least-recently greylisted peer, if the grey list is full. If peer was already in the list, it will become the most-recently greylisted, thus ensuring it is not evicted unfairly soon.

mem t peer returns true iff peer is greylisted.

list t: return the list peers added to the greylist