Merge remote-tracking branch 'upstream/master'

And optimize textures with optipng

init.lua

@@ -48,4 +48,6 @@ end
 
 if minetest.get_modpath("mtt") and mtt.enabled then
 	dofile(MP .. "/mtt.lua")
-end
+end
+
+minetest.log("action", "[scifi_nodes] loaded.")

nodes.json

@@ -122,8 +122,7 @@
         "description": "transparent metal floormesh",
         "texture_name": "mesh",
         "texture_modifier": "^[contrast:10:-50^[makealpha:0,0,0",
-        "drawtype": "glasslike",
+        "drawtype": "glasslike"
-        "sunlight_propagates": true
     },
     "pipe": {
         "description": "wall pipe"

nodes.lua

@@ -520,7 +520,6 @@ for name, def in pairs(nodes) do
 	local node_def = {
 		description = def.description,
 		drawtype = def.drawtype or "normal",
-		sunlight_propagates = def.sunlight_propagates,
 		tiles = tiles,
 		groups = {cracky=1, dig_generic = 3},
 		is_ground_content = false,