fix typos (#1644)

ethcore/src/blockchain/block_info.rs

@@ -38,7 +38,7 @@ pub enum BlockLocation {
 	/// It's not a part of the canon chain.
 	Branch,
 	/// It's part of the fork which should become canon chain,
-	/// because it's total difficulty is higher than current
+	/// because its total difficulty is higher than current
 	/// canon chain difficulty.
 	BranchBecomingCanonChain(BranchBecomingCanonChainData),
 }

ethcore/src/client/client.rs

@@ -1002,7 +1002,7 @@ impl MiningBlockChainClient for Client {
 			self.trie_factory.clone(),
 			false,	// TODO: this will need to be parameterised once we want to do immediate mining insertion.
 			self.state_db.lock().boxed_clone(),
-			&self.chain.block_header(&h).expect("h is best block hash: so it's header must exist: qed"),
+			&self.chain.block_header(&h).expect("h is best block hash: so its header must exist: qed"),
 			self.build_last_hashes(h.clone()),
 			author,
 			gas_range_target,

ethcore/src/miner/transaction_queue.rs

@@ -122,7 +122,7 @@ impl Ord for TransactionOrigin {
 }
 
 #[derive(Clone, Debug)]
-/// Light structure used to identify transaction and it's order
+/// Light structure used to identify transaction and its order
 struct TransactionOrder {
 	/// Primary ordering factory. Difference between transaction nonce and expected nonce in state
 	/// (e.g. Tx(nonce:5), State(nonce:0) -> height: 5)