fix: missing RawTransfer event emission (#77)

The `RawTransfer` event that's meant to enable offchain raw balance
tracking was incorrectly not emitted in certain cases, defeating its own
purpose. This commit fixes it.

Note that since it's impossible to apply the fix retrospectively,
users before this fix is deployed would have broken history. A separate
mechanism is needed to somehow "snapshot" raw balances of old users to
allow offchain indexing applications to reconcile accordingly.

src/z_token/external.cairo

@@ -200,11 +200,23 @@ fn mint(ref self: ContractState, to: ContractAddress, amount: felt252) -> bool {
     let raw_supply_after = safe_math::add(raw_supply_before, scaled_down_amount);
     self.raw_total_supply.write(raw_supply_after);
 
-    let amount: u256 = amount.into();
+    let amount_u256: u256 = amount.into();
     self
         .emit(
             contract::Event::Transfer(
-                contract::Transfer { from: contract_address_const::<0>(), to, value: amount }
+                contract::Transfer { from: contract_address_const::<0>(), to, value: amount_u256 }
+            )
+        );
+    self
+        .emit(
+            contract::Event::RawTransfer(
+                contract::RawTransfer {
+                    from: contract_address_const::<0>(),
+                    to,
+                    raw_value: scaled_down_amount,
+                    accumulator: accumulator,
+                    face_value: amount
+                }
             )
         );
 
@@ -227,11 +239,25 @@ fn burn(ref self: ContractState, user: ContractAddress, amount: felt252) {
     let raw_supply_after = safe_math::sub(raw_supply_before, scaled_down_amount);
     self.raw_total_supply.write(raw_supply_after);
 
-    let amount: u256 = amount.into();
+    let amount_256: u256 = amount.into();
     self
         .emit(
             contract::Event::Transfer(
-                contract::Transfer { from: user, to: contract_address_const::<0>(), value: amount }
+                contract::Transfer {
+                    from: user, to: contract_address_const::<0>(), value: amount_256
+                }
+            )
+        );
+    self
+        .emit(
+            contract::Event::RawTransfer(
+                contract::RawTransfer {
+                    from: user,
+                    to: contract_address_const::<0>(),
+                    raw_value: scaled_down_amount,
+                    accumulator: accumulator,
+                    face_value: amount
+                }
             )
         );
 }
@@ -259,6 +285,18 @@ fn burn_all(ref self: ContractState, user: ContractAddress) -> felt252 {
                 }
             )
         );
+    self
+        .emit(
+            contract::Event::RawTransfer(
+                contract::RawTransfer {
+                    from: user,
+                    to: contract_address_const::<0>(),
+                    raw_value: raw_balance,
+                    accumulator: accumulator,
+                    face_value: scaled_up_amount
+                }
+            )
+        );
 
     scaled_up_amount
 }