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).

core/bench_test.go

@@ -169,7 +169,6 @@ func benchInsertChain(b *testing.B, disk bool, gen func(int, *BlockGen)) {
 	// State and blocks are stored in the same DB.
 	evmux := new(event.TypeMux)
 	chainman, _ := NewBlockChain(db, FakePow{}, evmux)
-	chainman.SetProcessor(NewBlockProcessor(db, FakePow{}, chainman, evmux))
 	defer chainman.Stop()
 	b.ReportAllocs()
 	b.ResetTimer()