Merge pull request #299 from Perksey/patch-1

Update copyright headers
diff --git a/xml/gl.xml b/xml/gl.xml
index 8a325e3..3a2010f 100644
--- a/xml/gl.xml
+++ b/xml/gl.xml
@@ -1,7 +1,7 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <registry>
     <comment>
-Copyright (c) 2013-2018 The Khronos Group Inc.
+Copyright (c) 2013-2019 The Khronos Group Inc.
 
 Licensed under the Apache License, Version 2.0 (the "License");
 you may not use this file except in compliance with the License.
diff --git a/xml/glx.xml b/xml/glx.xml
index d9e504b..4ddd2f6 100644
--- a/xml/glx.xml
+++ b/xml/glx.xml
@@ -1,7 +1,7 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <registry>
     <comment>
-Copyright (c) 2013-2018 The Khronos Group Inc.
+Copyright (c) 2013-2019 The Khronos Group Inc.
 
 Licensed under the Apache License, Version 2.0 (the "License");
 you may not use this file except in compliance with the License.
diff --git a/xml/wgl.xml b/xml/wgl.xml
index 87e8fe2..88922eb 100644
--- a/xml/wgl.xml
+++ b/xml/wgl.xml
@@ -1,7 +1,7 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <registry>
     <comment>
-Copyright (c) 2013-2018 The Khronos Group Inc.
+Copyright (c) 2013-2019 The Khronos Group Inc.
 
 Licensed under the Apache License, Version 2.0 (the "License");
 you may not use this file except in compliance with the License.