New glass, glass stair/slab, and glass door textures

mods/doors/README.txt

@@ -46,8 +46,9 @@ Following textures created by sofar (CC-BY-SA-3.0):
 Obsidian door textures by red-001 based on textures by Pilzadam and BlockMen (CC BY-SA 3.0):
   door_obsidian_glass.png
 
-Glass door textures by red-001 based on textures by celeron55 (CC BY-SA 3.0):
-  door_glass.png
+Glass door textures by Krock based on textures by VanessaE (CC BY-SA 3.0):
+  doors_door_glass.png
+  doors_item_glass.png
 
 All other textures (created by PilzAdam) (CC BY-SA 3.0):