Move copyright to the top of files.

src/ftxui/dom/util.cpp

@@ -1,3 +1,6 @@
+// Copyright 2020 Arthur Sonzogni. All rights reserved.
+// Use of this source code is governed by the MIT license that can be found in
+// the LICENSE file.
 #include <algorithm>    // for min
 #include <functional>   // for function
 #include <memory>       // for __shared_ptr_access, make_unique
@@ -140,7 +143,3 @@ Element emptyElement() {
 }
 
 }  // namespace ftxui
-
-// Copyright 2020 Arthur Sonzogni. All rights reserved.
-// Use of this source code is governed by the MIT license that can be found in
-// the LICENSE file.