core: settable genesis nonce

You can set the nonce of the block with `--genesisnonce`. When the
genesis nonce changes and it doesn't match with the first block in your
database it will fail. A new `datadir` must be given if the nonce of the
genesis block changes.

core/block_processor_test.go

@@ -1,6 +1,7 @@
 package core
 
 import (
+	"fmt"
 	"math/big"
 	"testing"
 
@@ -16,7 +17,11 @@ func proc() (*BlockProcessor, *ChainManager) {
 	db, _ := ethdb.NewMemDatabase()
 	var mux event.TypeMux
 
-	chainMan := NewChainManager(db, db, thePow(), &mux)
+	genesis := GenesisBlock(0, db)
+	chainMan, err := NewChainManager(genesis, db, db, thePow(), &mux)
+	if err != nil {
+		fmt.Println(err)
+	}
 	return NewBlockProcessor(db, db, ezp.New(), chainMan, &mux), chainMan
 }