* accounts, cmd, eth, ethdb: port logs over to new system
* ethdb: drop concept of cache distribution between dbs
* eth: fix some log nitpicks to make them nicer
Shutting down geth prints hundreds of annoying error messages in some
cases. The errors appear because the Stop method of eth.ProtocolManager,
miner.Miner and core.TxPool is asynchronous. Left over peer sessions
generate events which are processed after Stop even though the database
has already been closed.
The fix is to make Stop synchronous using sync.WaitGroup.
For eth.ProtocolManager, in order to make use of WaitGroup safe, we need
a way to stop new peer sessions from being added while waiting on the
WaitGroup. The eth protocol Run function now selects on a signaling
channel and adds to the WaitGroup only if ProtocolManager is not
shutting down.
For miner.worker and core.TxPool the number of goroutines is static,
WaitGroup can be used in the usual way without additional
synchronisation.
Transactions are now propagated to peers from which we have not yet
received the transaction. This will significantly reduce the chatter on
the network.
Moved new mined block handler to the protocol handler and moved
transaction handling to protocol handler.
* Improved block propagation by sending blocks only to peers to which, as
far as we know, the peer does not know about.
* Made sub protocol its own manager
* SubProtocol now contains the p2p.Protocol which is used instead of
a function-returning-protocol thing.