updated external interfaces

Author: aalavandhan

spot-vaults/contracts/_interfaces/external/IBondController.sol

@@ -0,0 +1,5 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+// solhint-disable-next-line compiler-version
+interface IBondController {
+    function collateralBalance() external view returns (uint256);
+}

spot-vaults/contracts/_interfaces/external/IERC20.sol

@@ -0,0 +1,14 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+// solhint-disable-next-line compiler-version
+interface IERC20 {
+    function totalSupply() external view returns (uint256);
+    function balanceOf(address account) external view returns (uint256);
+    function transfer(address to, uint256 value) external returns (bool);
+    function allowance(address owner, address spender) external view returns (uint256);
+    function approve(address spender, uint256 value) external returns (bool);
+    function transferFrom(
+        address from,
+        address to,
+        uint256 value
+    ) external returns (bool);
+}

spot-vaults/contracts/_interfaces/external/IPerpFeePolicy.sol

@@ -0,0 +1,7 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+// solhint-disable-next-line compiler-version
+interface IPerpFeePolicy {
+    function decimals() external returns (uint8);
+    function deviationRatio() external returns (uint256);
+    function computePerpRolloverFeePerc(uint256 dr) external returns (int256);
+}

spot-vaults/contracts/_interfaces/external/IPerpetualTranche.sol

@@ -0,0 +1,13 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+// solhint-disable-next-line compiler-version
+interface IPerpetualTranche {
+    function underlying() external view returns (address);
+    function getTVL() external returns (uint256);
+    function totalSupply() external returns (uint256);
+    function getReserveCount() external returns (uint256);
+    function getReserveAt(uint256 index) external returns (address);
+    function deviationRatio() external returns (uint256);
+    function getReserveTokenValue(address t) external returns (uint256);
+    function getReserveTokenBalance(address t) external returns (uint256);
+    function feePolicy() external returns (address);
+}

spot-vaults/contracts/_interfaces/external/ITranche.sol

@@ -0,0 +1,6 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+// solhint-disable-next-line compiler-version
+interface ITranche {
+    function bond() external view returns (address);
+    function totalSupply() external view returns (uint256);
+}

spot-vaults/contracts/_interfaces/external/IWAMPL.sol

@@ -1,7 +1,5 @@
 // SPDX-License-Identifier: GPL-3.0-or-later
 // solhint-disable-next-line compiler-version
-pragma solidity ^0.7.6;
-
 interface IWAMPL {
     function wrapperToUnderlying(uint256 wamples) external view returns (uint256);
 }