Default: New mese texture. Add missing texture credits

Mese texture is a classic-mese-yellow version
of celeron55's texture used in MTv0.4.0
Add missing texture credits for mese crystal
and mese crystal fragment

mods/default/README.txt

@@ -58,6 +58,8 @@ VanessaE (WTFPL):
   default_desert_sand.png
   default_desert_stone.png
   default_sand.png
+  default_mese_crystal.png
+  default_mese_crystal_fragment.png
 
 Calinou (CC BY-SA):
   default_brick.png
@@ -121,6 +123,7 @@ paramat (CC BY-SA 3.0):
   default_grass.png
   default_grass_side.png
   default_snow_side.png
+  default_mese_block.png
 
 brunob.santos (CC BY-SA 4.0):
   default_desert_cobble.png