make some depends optional

jungletree/depends.txt

@@ -1,2 +1 @@
 default
-habitat

sumpf/birke.lua

@@ -207,7 +207,7 @@ minetest.register_abm({
 })
 
 if sumpf.spawn_plants
-and minetest.get_modpath("habitat") then
+and habitat then
 	habitat:generate("sumpf:sapling", {"default:dirt_with_grass"},
 		minp, maxp, 20, 25, 100, 500, {"default:water_source"},30,{"default:desert_sand"})
 	habitat:generate("sumpf:gras", {"default:dirt_with_grass"},

sumpf/depends.txt

@@ -1,6 +1,6 @@
 default
 riesenpilz
 jungletree
-habitat
-bucket
-stairs
+bucket?
+habitat?
+stairs?

sumpf/init.lua

@@ -93,6 +93,7 @@ minetest.register_node("sumpf:sumpf2", {
 
 ----------------------stairs and slabs------------------
 
+if stairs then
 	stairs.register_stair_and_slab("swampstone", "sumpf:junglestone",
 			{cracky=3},
 			{"sumpf_swampstone.png"},
@@ -116,6 +117,7 @@ stairs.register_stair_and_slab("swampstonebrick", "sumpf:junglestonebrick",
 			"Swamp Stone Brick Slab",
 			default.node_sound_stone_defaults()
 	)
+end
 
 ---------------------------------------------------------
 
@@ -180,6 +182,7 @@ minetest.register_node("sumpf:dirtywater_source", {
 	groups = {water=3, liquid=3, puts_out_fire=1},
 })
 
+if bucket then
 	bucket.register_liquid(
 		"sumpf:dirtywater_source",
 		"sumpf:dirtywater_flowing",
@@ -187,6 +190,7 @@ bucket.register_liquid(
 		"bucket.png^sumpf_bucket_dirtywater.png",
 		"Swampwater Bucket"
 	)
+end
 
 
 sumpf = {}