Added some methods to comply to the PoW block interface

ethchain/block.go

@@ -348,10 +348,18 @@ func NewUncleBlockFromValue(header *ethutil.Value) *Block {
 	return block
 }
 
+func (block *Block) Trie() *ethrie.Trie {
+	return block.state.Trie
+}
+
 func (block *Block) GetRoot() interface{} {
 	return block.state.Trie.Root
 }
 
+func (block *Block) Diff() *big.Int {
+	return block.Difficulty
+}
+
 func (self *Block) Receipts() []*Receipt {
 	return self.receipts
 }