pass Pubkeys as refs, copy only where values needed (#3213)

* pass Pubkeys as refs, copy only where values needed

* Pubkey is pervasive

* fixup

sdk/src/account.rs

@@ -40,11 +40,11 @@ impl fmt::Debug for Account {
 
 impl Account {
     // TODO do we want to add executable and leader_owner even though they should always be false/default?
-    pub fn new(lamports: u64, space: usize, owner: Pubkey) -> Account {
+    pub fn new(lamports: u64, space: usize, owner: &Pubkey) -> Account {
         Account {
             lamports,
             userdata: vec![0u8; space],
-            owner,
+            owner: *owner,
             executable: false,
         }
     }