all: Rename crypto.Sha3{,Hash}() to crypto.Keccak256{,Hash}()

As we aren't really using the standarized SHA-3

trie/secure_trie_test.go

@@ -63,7 +63,7 @@ func TestSecureGetKey(t *testing.T) {
 
 	key := []byte("foo")
 	value := []byte("bar")
-	seckey := crypto.Sha3(key)
+	seckey := crypto.Keccak256(key)
 
 	if !bytes.Equal(trie.Get(key), value) {
 		t.Errorf("Get did not return bar")

trie/trie.go

@@ -40,7 +40,7 @@ var (
 	emptyRoot = common.HexToHash("56e81f171bcc55a6ff8345e692c0f86e5b48e01b996cadc001622fb5e363b421")
 
 	// This is the known hash of an empty state trie entry.
-	emptyState = crypto.Sha3Hash(nil)
+	emptyState = crypto.Keccak256Hash(nil)
 )
 
 // ClearGlobalCache clears the global trie cache