IAssetProxyDispatcher to IAssetProxy in MixinSettlement layer + allowing 0-condition in ERC721 transfer

packages/contracts/src/contracts/current/protocol/AssetProxyDispatcher/proxies/ERC721Proxy.sol

@@ -42,6 +42,9 @@ contract ERC721Proxy is
         public
         onlyAuthorized
     {
+        // No work to do
+        if (amount == 0) return;
+
         // Decode metadata
         address token;
         uint256 tokenId;

packages/contracts/src/contracts/current/protocol/Exchange/Exchange.sol

@@ -37,7 +37,7 @@ contract Exchange is
     function Exchange(
         IToken _zrxToken,
         bytes _zrxProxyMetadata,
-        IAssetProxyDispatcher _assetProxyDispatcher)
+        IAssetProxy _assetProxyDispatcher)
         public
         MixinExchangeCore()
         MixinSignatureValidator()

packages/contracts/src/contracts/current/protocol/Exchange/MixinSettlementProxy.sol

@@ -22,20 +22,20 @@ pragma experimental ABIEncoderV2;
 import "./mixins/MSettlement.sol";
 import "../../tokens/Token/IToken.sol";
 import "./LibPartialAmount.sol";
-import "../AssetProxyDispatcher/IAssetProxyDispatcher.sol";
+import "../AssetProxyDispatcher/IAssetProxy.sol";
 
 /// @dev Provides MixinSettlement
 contract MixinSettlementProxy is
     MSettlement,
     LibPartialAmount
 {
-    IAssetProxyDispatcher TRANSFER_PROXY;
+    IAssetProxy TRANSFER_PROXY;
     bytes ZRX_PROXY_METADATA;
     IToken ZRX_TOKEN;
 
     function transferProxy()
         public view
-        returns (IAssetProxyDispatcher)
+        returns (IAssetProxy)
     {
         return TRANSFER_PROXY;
     }
@@ -55,7 +55,7 @@ contract MixinSettlementProxy is
     }
 
     function MixinSettlementProxy(
-        IAssetProxyDispatcher assetProxyDispatcherContract,
+        IAssetProxy assetProxyDispatcherContract,
         IToken zrxToken,
         bytes zrxProxyMetadata)
         public
@@ -65,8 +65,6 @@ contract MixinSettlementProxy is
         ZRX_PROXY_METADATA = zrxProxyMetadata;
     }
 
-
-
     function settleOrder(
         Order memory order,
         address takerAddress,