eth, trie: removed key prefixing from state entries & merge db fix

Fixed database merge strategy to use the correct database. Due to a copy
paste fail when doing type evaluation the same database was being
iterated (chain), all others were ignored.

Removed state prefixing because {H(code): code} is stored in the same
database as the rest of the state.

trie/trie.go

@@ -27,8 +27,6 @@ import (
 	"github.com/ethereum/go-ethereum/crypto"
 )
 
-var StatePre = []byte("state-")
-
 func ParanoiaCheck(t1 *Trie, backend Backend) (bool, *Trie) {
 	t2 := New(nil, backend)