Add air shield, change time to float value

Air Shield gives off light and can be walked through. Use for doors,
etc.
Time changed from 4500 to 0.1875, which is the same but more compatible
with dev builds.

mods/moontest/nodes.lua

@@ -69,6 +69,25 @@ minetest.register_node("moontest:air", {
 	buildable_to = true,
 })
 
+minetest.register_node("moontest:air_shield", {
+	description = "Air Shield",
+	drawtype = "glasslike",
+	inventory_image = minetest.inventorycube("moontest_air_shield.png"),
+	use_texture_alpha = true,
+	--tiles = {"moontest_air_shield.png"},
+	tiles = {
+		{name="moontest_air_shield_animated.png", animation={type="vertical_frames", aspect_w=16, aspect_h=16, length=3.0}}
+	},
+	paramtype = "light",
+	sunlight_propagates = true,
+	light_source = 7,
+	walkable = false,
+	pointable = false,
+	diggable = false,
+	buildable_to = true,
+	post_effect_color = {a=100, r=0, g=150, b=255},
+})
+
 minetest.register_node("moontest:airgen", {
 	description = "Air Generator",
 	tiles = {"moontest_airgen.png"},

mods/sky/init.lua

@@ -1,7 +1,7 @@
 
 -- Set time to midnight.
 minetest.register_on_joinplayer(function(player)
-    minetest.set_timeofday(4500)
+    minetest.set_timeofday(0.1875)
     minetest.setting_set("time_speed", 0)
 end)