Add liquid drop

Thanks for the convo and lessons, @hecktest.

mods/jas0/abm.lua

@@ -0,0 +1,39 @@
+-- Dedicated to hecks!
+
+local random = math.random
+local liquids = {
+	"default:water_source",
+	"default:river_water_source",
+	"default:lava_source",
+}
+local liquid_drop = function(pos, node)
+	local n = node.name
+	local p = {
+		x = pos.x,
+		y = pos.y - 1,
+		z = pos.z,
+	}
+	local py = minetest.get_node_or_nil(p)
+	if py and py.name and
+			(py.name == n:sub(1, -7) .. "flowing" or
+			py.name == "air") then
+		minetest.set_node(pos, {name = "air"})
+		minetest.set_node(p, {name = n})
+	end
+end
+
+for i = 1, #liquids do
+	local liq = liquids[i]
+	minetest.register_abm({
+		label = liq .. " drop",
+		nodenames = {liq},
+		neighbors = {liq:sub(1, -7) .. "flowing"},
+		interval = 3.6,
+		chance = 1,
+		catch_up = false,
+		action = function(pos, node, active_object_count, active_object_count_wider)
+			local r1, r2 = random(), random()
+			minetest.after(r1 + r2, liquid_drop, pos, node)
+		end,
+	})
+end

mods/jas0/init.lua

@@ -105,3 +105,4 @@ dofile(mod_path .. "/players.lua")
 dofile(mod_path .. "/classes.lua")
 dofile(mod_path .. "/recipes.lua")
 dofile(mod_path .. "/chatcommands.lua")
+dofile(mod_path .. "/abm.lua")