Merge pull request 'Implement water freezing (mostly taken from mcla)' (#4478) from WillConker/VoxeLibre:water_freezing into master

Reviewed-on: VoxeLibre/VoxeLibre#4478
Reviewed-by: Mikita Wiśniewski <rudzik8@protonmail.com>

mods/ITEMS/mcl_core/functions.lua

@@ -1451,6 +1451,22 @@ minetest.register_abm({
 	end
 })
 
+-- Freeze water
+minetest.register_abm({
+	label = "Freeze water in cold areas",
+	nodenames = {"mcl_core:water_source", "mclx_core:river_water_source"},
+	interval = 32,
+	chance = 8,
+	action = function(pos, node)
+		if mcl_weather.has_snow(pos)
+				and minetest.get_natural_light(vector.offset(pos,0,1,0), 0.5) == minetest.LIGHT_MAX + 1
+				and minetest.get_artificial_light(minetest.get_node(pos).param1) < 10 then
+			node.name = "mcl_core:ice"
+			minetest.swap_node(pos, node)
+		end
+	end
+})
+
 --[[ Call this for vines nodes only.
 Given the pos and node of a vines node, this returns true if the vines are supported
 and false if the vines are currently floating.