core: during chain reorg rewrite receipts and transactions

Added PutBlockReceipts; storing receipts by blocks. Eventually this will
require pruning during some cleanup cycle. During forks the receipts by
block are used to get the new canonical receipts and transactions.

This PR fixes #1473 by rewriting transactions and receipts from the point
of where the fork occured.

core/chain_manager.go

@@ -667,6 +667,8 @@ func (self *ChainManager) InsertChain(chain types.Blocks) (int, error) {
 			queue[i] = ChainSplitEvent{block, logs}
 			queueEvent.splitCount++
 		}
+		PutBlockReceipts(self.extraDb, block, receipts)
+
 		stats.processed++
 	}
 
@@ -744,7 +746,12 @@ func (self *ChainManager) merge(oldBlock, newBlock *types.Block) error {
 	// insert blocks. Order does not matter. Last block will be written in ImportChain itself which creates the new head properly
 	self.mu.Lock()
 	for _, block := range newChain {
+		// insert the block in the canonical way, re-writing history
 		self.insert(block)
+		// write canonical receipts and transactions
+		PutTransactions(self.extraDb, block, block.Transactions())
+		PutReceipts(self.extraDb, GetBlockReceipts(self.extraDb, block.Hash()))
+
 	}
 	self.mu.Unlock()