Added crystal crafts and spawning

fixes #141

mods/mapgen/crafts.lua

@@ -1,4 +1,17 @@
 
+minetest.register_craft( {
+	output = "mapgen:crystal_shard 4",
+	recipe = {
+		{ "mapgen:crystal",},
+	}
+})
+
+minetest.register_craft( {
+	output = "mapgen:crystal_shard 2",
+	recipe = {
+		{ "mapgen:crystal_small",},
+	}
+})
 
 minetest.register_craft( {
 	output = "decoblocks:bamboo_block 4",

mods/mapgen/mapgen.lua

@@ -2900,6 +2900,26 @@ minetest.register_on_generated(function(minp, maxp)
 	end
 end)
 
+minetest.register_on_generated(function(minp, maxp)
+	if maxp.y < -2000 or maxp.y > 1500 then
+		return
+	end
+	local stone = minetest.find_nodes_in_area(minp, maxp,
+		{"default:stone"})
+	for n = 1, #stone do
+		if math.random(1, 150) == 1 then
+			local pos = {x = stone[n].x, y = stone[n].y, z = stone[n].z }
+				if minetest.get_node({x=pos.x, y=pos.y+1, z=pos.z}).name == "air" then
+					if math.random(1,5) == 1 then
+					minetest.add_node({x=pos.x, y=pos.y+1, z=pos.z}, {name = "mapgen:crystal_small"})
+					else
+					minetest.add_node({x=pos.x, y=pos.y+1, z=pos.z}, {name = "mapgen:crystal"})
+					end
+				end
+		end
+	end
+end)
+
 --underground dungeons
 
 local dungeon_rarity = 1000