Integrate sum trees with the rest of the system (#116)

* Integrate PMMR and its persistent backend with the Chain
* Chain can set tree roots; PMMR backend discard
* Check spent and prune for each input in new block
* Handling of forks by rewinding the state
* More PMMR tests and fixes, mostly around rewind
* Rewrite get_unspent to use the sumtrees, fix remaining compilation issues

pool/src/graph.rs

@@ -25,6 +25,7 @@ use rand;
 use std::fmt;
 
 use core::core;
+use core::core::hash::Hashed;
 
 /// An entry in the transaction pool.
 /// These are the vertices of both of the graph structures
@@ -214,7 +215,8 @@ impl DirectedGraph {
 /// proofs and any extra data the kernel may cover, but it is used initially
 /// for testing purposes.
 pub fn transaction_identifier(tx: &core::transaction::Transaction) -> core::hash::Hash {
-    core::transaction::merkle_inputs_outputs(&tx.inputs, &tx.outputs)
+    // core::transaction::merkle_inputs_outputs(&tx.inputs, &tx.outputs)
+		tx.hash()
 }
 
 #[cfg(test)]