Peer interface cleanup - no functionality change
When sending own transactions using Node::post(txn) sometime they are stuck in sending - like all of them are stuck in sending.
Some improvements that could fix this:
1. when resending we also announce again to all peers
2. we are cleaning up better in the inv to send
3. we are flushing in case of a resend
Still, it seems like a node can end in a state where it only receives transactions and blocks, but never is able to send them - boost problem ?
Bug fix: We were never sending Pings - we started the suicide timer instead!