implement address and msg.sender

Signed-off-by: Cyrill Leutwiler <bigcyrill@hotmail.com>

crates/integration/contracts/Baseline.sol

@@ -1,6 +1,6 @@
 // SPDX-License-Identifier: MIT
 
-pragma solidity ^0.8.24;
+pragma solidity ^0.8;
 
 contract Baseline {
     function baseline() public payable {}

crates/integration/contracts/Block.sol

@@ -1,6 +1,6 @@
 // SPDX-License-Identifier: MIT
 
-pragma solidity ^0.8.24;
+pragma solidity ^0.8;
 
 contract Block {
     function timestamp() public view returns (uint ret) {

crates/integration/contracts/Computation.sol

@@ -1,6 +1,6 @@
 // SPDX-License-Identifier: MIT
 
-pragma solidity ^0.8.24;
+pragma solidity ^0.8;
 
 contract Computation {
     function triangle_number(int64 n) public pure returns (int64 sum) {

crates/integration/contracts/Context.sol

@@ -0,0 +1,13 @@
+// SPDX-License-Identifier: MIT
+
+pragma solidity ^0.8;
+
+contract Context {
+    function address_this() public view returns (address ret) {
+        ret = address(this);
+    }
+
+    function caller() public view returns (address ret) {
+        ret = msg.sender;
+    }
+}

crates/integration/contracts/ERC20.sol

@@ -1,6 +1,6 @@
 // SPDX-License-Identifier: MIT
 
-pragma solidity ^0.8.20;
+pragma solidity ^0.8;
 
 // https://github.com/OpenZeppelin/openzeppelin-contracts/blob/v3.0.0/contracts/token/ERC20/IERC20.sol
 interface IERC20 {

crates/integration/contracts/Fibonacci.sol

@@ -1,6 +1,6 @@
 // SPDX-License-Identifier: UNLICENSED
 
-pragma solidity ^0.8.24;
+pragma solidity ^0.8;
 
 // https://medium.com/coinmonks/fibonacci-in-solidity-8477d907e22a
 

crates/integration/contracts/MSize.sol

@@ -1,6 +1,6 @@
 // SPDX-License-Identifier: MIT
 
-pragma solidity ^0.8.24;
+pragma solidity ^0.8;
 
 contract MSize {
     uint[] public data;

crates/integration/contracts/Value.sol

@@ -1,6 +1,6 @@
 // SPDX-License-Identifier: MIT
 
-pragma solidity ^0.8.24;
+pragma solidity ^0.8;
 
 contract Value {
     function value() public payable returns (uint ret) {

crates/integration/contracts/flipper.sol

@@ -1,5 +1,5 @@
 // SPDX-License-Identifier: MIT
-pragma solidity ^0.8.24;
+pragma solidity ^0.8;
 
 contract Flipper {
     bool coin;

crates/integration/contracts/mStore8.sol

@@ -1,6 +1,6 @@
 // SPDX-License-Identifier: MIT
 
-pragma solidity ^0.8.24;
+pragma solidity ^0.8;
 
 contract MStore8 {
     function mStore8(uint value) public pure returns (uint256 word) {