- expose info about number of txns in unbroadcast set and whether a mempool entry's tx has passed initial broadcast
- makes rpcs more informative and allows for more explicit testing, eg tracking if tx is in unbroadcast set
before and after originating node connects to peers (adds this in mempool_unbroadcast.py)
- adds mempool method IsUnbroadcastTx to query for tx inclusion in mempool's unbroadcast set
Check that...
- mempool tracks & reattempts delivery of a transaction where a GETDATA hasn't
been requested by a peer yet.
- transaction delivery is not attempted again after GETDATA is received.
- transaction is removed from the unbroadcast set when its removed from the
mempool.
