core, eth, rpc: split out block validator and state processor

This removes the burden on a single object to take care of all
validation and state processing. Now instead the validation is done by
the `core.BlockValidator` (`types.Validator`) that takes care of both
header and uncle validation through the `ValidateBlock` method and state
validation through the `ValidateState` method. The state processing is
done by a new object `core.StateProcessor` (`types.Processor`) and
accepts a new state as input and uses that to process the given block's
transactions (and uncles for rewords) to calculate the state root for
the next block (P_n + 1).

cmd/utils/flags.go

@@ -557,8 +557,6 @@ func MakeChain(ctx *cli.Context) (chain *core.BlockChain, chainDb ethdb.Database
 		Fatalf("Could not start chainmanager: %v", err)
 	}
 
-	proc := core.NewBlockProcessor(chainDb, pow, chain, eventMux)
-	chain.SetProcessor(proc)
 	return chain, chainDb
 }