Add license identifier in headers

src/cat.sol

@@ -1,3 +1,5 @@
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
 /// cat.sol -- Dai liquidation module
 
 // Copyright (C) 2018 Rain <[email protected]>

src/dai.sol

@@ -1,3 +1,5 @@
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
 // Copyright (C) 2017, 2018, 2019 dbrock, rain, mrchico
 
 // This program is free software: you can redistribute it and/or modify

src/end.sol

@@ -1,3 +1,5 @@
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
 /// end.sol -- global settlement engine
 
 // Copyright (C) 2018 Rain <[email protected]>

src/flap.sol

@@ -1,3 +1,5 @@
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
 /// flap.sol -- Surplus auction
 
 // Copyright (C) 2018 Rain <[email protected]>

src/flip.sol

@@ -1,3 +1,5 @@
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
 /// flip.sol -- Collateral auction
 
 // Copyright (C) 2018 Rain <[email protected]>

src/flop.sol

@@ -1,3 +1,5 @@
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
 /// flop.sol -- Debt auction
 
 // Copyright (C) 2018 Rain <[email protected]>

src/join.sol

@@ -1,3 +1,5 @@
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
 /// join.sol -- Basic token adapters
 
 // Copyright (C) 2018 Rain <[email protected]>

src/jug.sol

@@ -1,3 +1,5 @@
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
 /// jug.sol -- Dai Lending Rate
 
 // Copyright (C) 2018 Rain <[email protected]>

src/lib.sol

@@ -1,3 +1,5 @@
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
 // This program is free software: you can redistribute it and/or modify
 // it under the terms of the GNU General Public License as published by
 // the Free Software Foundation, either version 3 of the License, or

src/pot.sol

@@ -1,3 +1,5 @@
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
 /// pot.sol -- Dai Savings Rate
 
 // Copyright (C) 2018 Rain <[email protected]>

src/spot.sol

@@ -1,3 +1,5 @@
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
 /// spot.sol -- Spotter
 
 // This program is free software: you can redistribute it and/or modify

src/test/dai.t.sol

@@ -1,3 +1,5 @@
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
 /// erc20.t.sol -- test for erc20.sol
 
 // Copyright (C) 2015-2019  DappHub, LLC

src/test/end.t.sol

@@ -1,3 +1,5 @@
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
 // end.t.sol -- global settlement tests
 
 // Copyright (C) 2018 Rain <[email protected]>

src/vat.sol

@@ -1,3 +1,5 @@
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
 /// vat.sol -- Dai CDP database
 
 // Copyright (C) 2018 Rain <[email protected]>

src/vow.sol

@@ -1,3 +1,5 @@
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
 /// vow.sol -- Dai settlement module
 
 // Copyright (C) 2018 Rain <[email protected]>