Minor update of smart contracts

Author: Pafaul

contracts/SwapPair/SwapPairContract.sol

@@ -302,9 +302,9 @@ contract SwapPairContract is ITokensReceivedCallback, ISwapPairInformation, IUpg
         external
         responsible
         view
-        returns (uint128, uint128)
+        returns (LiquidityPoolsInfo)
     {
-        return (lps[T1], lps[T2]);
+        return LiquidityPoolsInfo(lps[T1], lps[T2], liquidityTokensMinted);
     }
 
     //============Functions for offchain execution============

contracts/SwapPair/interfaces/swapPair/ISwapPairContract.sol

@@ -13,7 +13,7 @@ interface ISwapPairContract is ISwapPairInformation {
         uint128 swappableTokenAmount
     ) external responsible view returns (SwapInfo _swapInfo);
 
-    function getCurrentExchangeRate() external responsible view returns (uint128, uint128);
+    function getCurrentExchangeRate() external responsible view returns (LiquidityPoolsInfo);
 
     function getPairInfo() external responsible view returns (SwapPairInfo info);
 

contracts/SwapPair/interfaces/swapPair/ISwapPairInformation.sol

@@ -20,6 +20,13 @@ interface ISwapPairInformation {
         uint32  swapPairCodeVersion;    // code version of swap pair. can be upgraded using root contract
     }
 
+    // Information about liquidity pools volumes
+    struct LiquidityPoolsInfo {
+        uint128 lp1;            // volume of first LP
+        uint128 lp2;            // volume of second LP
+        uint256 lpTokensMinted; // amount of minted LP tokens 
+    }
+
     // Information about swap operation result
     struct SwapInfo {
         uint128 swappableTokenAmount; // token amount that will be swapped