Xpanes: Use opaque texture for top+bottom of iron bar (#1357)

- Use opaque texture for top+bottom of iron bar
- Add color variation for iron bar top/bottom
- Add paramat's texture to credits
- Update license info for paramat's textures

mods/xpanes/README.txt

@@ -16,3 +16,6 @@ xyz (CC BY-SA 3.0):
 
 Gambit (CC BY-SA 3.0):
   xpanes_bar.png
+
+paramat (CC BY-SA 3.0):
+  xpanes_bar_top.png

mods/xpanes/init.lua

@@ -160,7 +160,7 @@ xpanes.register_pane("pane", {
 
 xpanes.register_pane("bar", {
 	description = "Iron bar",
-	textures = {"xpanes_bar.png","xpanes_bar.png","xpanes_space.png"},
+	textures = {"xpanes_bar.png","xpanes_bar.png","xpanes_bar_top.png"},
 	inventory_image = "xpanes_bar.png",
 	wield_image = "xpanes_bar.png",
 	groups = {cracky=2},

mods/xpanes/license.txt

@@ -33,6 +33,7 @@ Licenses of media (textures)
 Attribution-ShareAlike 3.0 Unported (CC BY-SA 3.0)
 Copyright (C) 2014-2016 xyz
 Copyright (C) 2013-2016 Gambit
+Copyright (C) 2016 paramat
 
 You are free to:
 Share — copy and redistribute the material in any medium or format.