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/cache.go

@@ -38,8 +38,6 @@ func NewCache(backend Backend) *Cache {
 }
 
 func (self *Cache) Get(key []byte) []byte {
-	key = append(StatePre, key...)
-
 	data := self.store[string(key)]
 	if data == nil {
 		data, _ = self.backend.Get(key)
@@ -49,8 +47,6 @@ func (self *Cache) Get(key []byte) []byte {
 }
 
 func (self *Cache) Put(key []byte, data []byte) {
-	key = append(StatePre, key...)
-
 	self.batch.Put(key, data)
 	self.store[string(key)] = data
 }