move the cow wrapper file out of vendor, and update the docs a bit more

Author: kaze-cow

src/vendor/CowWrapper.sol renamed to src/CowWrapper.sol

@@ -2,6 +2,17 @@
 pragma solidity >=0.7.6 <0.9.0;
 pragma abicoder v2;
 
+/**
+ * @title CoW Wrapper all-in-one integration file
+ * @author CoW Protocol Developers
+ * @notice This file is completely self-contained (ie no dependencies) and can be portably copied to whatever projects it is needed.
+ * It contains:
+ * * CowWrapper -- an abstract base contract which should be inherited by all wrappers
+ * * ICowWrapper -- the required interface for all wrappers
+ * * ICowSettlement -- A minimized interface and base structures for CoW Protocol settlement contract. From https://github.com/cowprotocol/contracts/blob/main/src/contracts/GPv2Settlement.sol
+ * * ICowAuthentication -- The authentication interface used by ICowSettlement. From https://github.com/cowprotocol/contracts/blob/main/src/contracts/interfaces/GPv2Authentication.sol
+ */
+
 /// @title CoW Protocol Authentication Interface
 /// @author CoW DAO developers
 interface ICowAuthentication {
@@ -105,7 +116,7 @@ abstract contract CowWrapper is ICowWrapper {
     ///      validates wrapper data, then delegates to _wrap() for custom logic.
     /// @param settleData ABI-encoded call to ICowSettlement.settle() containing trade data
     /// @param wrapperData Encoded data for this wrapper and the chain of next wrappers/settlement.
-    ///                    Format: [len][wrapper-specific-data][next-address]([len][wrapper-specific-data][next-address]...)
+    ///                    Format: [2-byte len][wrapper-specific-data][next-address]([2-byte len][wrapper-specific-data][next-address]...)
     function wrappedSettle(bytes calldata settleData, bytes calldata wrapperData) external {
         // Revert if not a valid solver
         require(AUTHENTICATOR.isSolver(msg.sender), NotASolver(msg.sender));

test/CowWrapper.t.sol

@@ -2,7 +2,7 @@
 pragma solidity ^0.8;
 
 import {Test} from "forge-std/Test.sol";
-import {CowWrapper, ICowSettlement, ICowAuthentication} from "../src/vendor/CowWrapper.sol";
+import {CowWrapper, ICowSettlement, ICowAuthentication} from "../src/CowWrapper.sol";
 import {IERC20, GPv2Trade, GPv2Interaction} from "cow/GPv2Settlement.sol";
 import {EmptyWrapper} from "./EmptyWrapper.sol";
 

test/EmptyWrapper.sol

@@ -2,7 +2,7 @@
 pragma solidity ^0.8;
 pragma abicoder v2;
 
-import {ICowSettlement, CowWrapper} from "../src/vendor/CowWrapper.sol";
+import {ICowSettlement, CowWrapper} from "../src/CowWrapper.sol";
 
 contract EmptyWrapper is CowWrapper {
     string public override name = "Empty Wrapper";

test/helpers/CowWrapperHelpers.sol

@@ -1,7 +1,7 @@
 // SPDX-License-Identifier: GPL-3.0-or-later
 pragma solidity ^0.8;
 
-import {ICowSettlement, ICowAuthentication, ICowWrapper} from "src/vendor/CowWrapper.sol";
+import {ICowSettlement, ICowAuthentication, ICowWrapper} from "src/CowWrapper.sol";
 
 library CowWrapperHelpers {
     struct SettleCall {