Fix tree trunk stone inclusions

Allow nodes to be ignored from the "remove
unsupported falling nodes in mapgen" hack, and
register things that don't make sense to convert
to stone ever for this exemption.

mods/nc_api/item_groupdump.lua

@@ -59,6 +59,7 @@ local groups = {
 	dynamic_light = "light level of invisible dynamic lights from nc_api_active",
 	ember = "(specific) fuel level of burning nc_fire embers",
 	falling_node = "built-in: falls as a node if not supported below",
+	falling_mapgen_ignore = "falling nodes that are ignored by mapgen falling node removal",
 	falling_repose = "angle of repose for falling nodes, higher is steeper",
 	fire_fuel = "for flammable nodes, convert into ember of this grade (1-8)",
 	firestick = "can be rubbed against another firestick to make fire; success rate factor",

mods/nc_lantern/node.lua

@@ -45,6 +45,7 @@ local function reg(level)
 				lux_emit = math_ceil(level / 2),
 				stack_as_node = 1,
 				falling_node = 1,
+				falling_mapgen_ignore = 1,
 			},
 			stack_max = 1,
 			light_source = level * 2,

mods/nc_lode/ladder.lua

@@ -27,6 +27,7 @@ nodecore.register_lode("Ladder", {
 		sunlight_propagates = true,
 		groups = {
 			falling_node = 1,
+			falling_mapgen_ignore = 1,
 			chisel = 2,
 			optic_opaque = 1,
 		},

mods/nc_lode/metallurgy.lua

@@ -39,6 +39,8 @@ function nodecore.register_lode(shape, rawdef)
 					cracky = 3,
 					metallic = 1,
 					falling_node = temper.name == "hot" and 1 or nil,
+					falling_mapgen_ignore = temper.name == "hot"
+					and 1 or nil,
 					["lode_temper_" .. temper.name] = 1
 				},
 				["lode_temper_" .. temper.name] = true,
@@ -53,6 +55,7 @@ function nodecore.register_lode(shape, rawdef)
 			def.light_source = nil
 		else
 			def.groups.falling_node = 1
+			def.groups.falling_mapgen_ignore = 1
 			def.groups.damage_pickup = 1
 			def.groups.damage_radiant = 1
 		end

mods/nc_nodefall/mapfix.lua

@@ -15,7 +15,8 @@ local function initdata()
 		if v.walkable and not v.buildable_to then
 			idsupport[minetest.get_content_id(k)] = true
 		end
-		if ((v.groups or {}).falling_node or 0) > 0 then
+		if ((v.groups or {}).falling_node or 0) > 0
+		and ((v.groups or {}).falling_mapgen_ignore or 0) <= 0 then
 			idfalling[minetest.get_content_id(k)] = true
 		end
 	end

mods/nc_optics/glass.lua

@@ -48,6 +48,7 @@ minetest.register_node(modname .. ":glass_crude", {
 		groups = {
 			silica = 1,
 			falling_node = 1,
+			falling_mapgen_ignore = 1,
 			crumbly = 2,
 			scaling_time = 150
 		},

mods/nc_sponge/node.lua

@@ -32,6 +32,7 @@ minetest.register_node(modname .. ":sponge_wet", {
 			crumbly = 2,
 			coolant = 1,
 			falling_node = 1,
+			falling_mapgen_ignore = 1,
 			moist = 1,
 			sponge = 1
 		},

mods/nc_stonework/bricks.lua

@@ -47,6 +47,7 @@ function nodecore.register_stone_bricks(name, desc, tile, alpha, bondalpha,
 	bonded = nodecore.underride(bonded, groups)
 	bonded.stone_bricks = 2
 	bonded.falling_node = nil
+	bonded.falling_mapgen_ignore = nil
 	minetest.register_node(":" .. modname .. ":bricks_" .. name .. "_bonded", {
 			description = "Bonded " .. desc .. " Bricks",
 			tiles = {tile .. "^(" .. modname .. "_bricks.png^[opacity:"

mods/nc_tree/grow_node.lua

@@ -114,6 +114,7 @@ minetest.register_node(modname .. ":tree_bud", {
 			flammable = 12,
 			fire_fuel = 6,
 			falling_node = 1,
+			falling_mapgen_ignore = 1,
 			scaling_time = 80,
 			leaf_decay_support = 1
 		},

mods/nc_tree/node.lua

@@ -57,6 +57,7 @@ minetest.register_node(modname .. ":tree", {
 			fire_fuel = 6,
 			log = 1,
 			falling_node = 1,
+			falling_mapgen_ignore = 1,
 			scaling_time = 80,
 			leaf_decay_support = 1
 		},

mods/nc_woodwork/ladder.lua

@@ -27,6 +27,7 @@ minetest.register_node(modname .. ":ladder", {
 			flammable = 2,
 			fire_fuel = 1,
 			falling_node = 1,
+			falling_mapgen_ignore = 1,
 			optic_opaque = 1,
 		},
 		crush_damage = 0.25,