Add quarry:gravel node.

README.md

@@ -19,9 +19,29 @@ What do I mean by that?
 - For building, a Trowel and Mortar tool is provided. It can mortar placed cobble nodes into stonebrick nodes, and mortar placed cut\_stone nodes back into stone nodes.
 
 
+Special notes
+-------------
+
+**What happens when this mod is installed in an existing world?**
+
+- Existing cobble nodes will fall when touched. This is problematic since dungeons have cobble ceilings.
+
+- Hamlet's stonebrick\_dungeons is a required dependency to deal with this problem, but it only works on newly-made dungeons, not preexisting ones.
+
+- In addition, quarry currently only supports Minetest default game. It's likely that there are other mods that will conflict with this mod.
+
+**What happens when this mod is removed from a world?**
+
+- Cobble will stop being a falling node.
+
+- And just like every other mod, all tools and nodes defined in this mod will become unknown.
+ 
+
 Additional notes
 ----------------
 
+- **New:** default:gravel now turns into quarry:gravel when dug. This is to prevent digging through the same gravel nodes over and over to find flint. (The texture is slightly lighter.)
+
 - Cobble cannot be converted back into stone by melting it in a furnace.
 
 - A Quarry Hammer is only able to cut out a stone if it has at least two faces open to the air (to be able to cut all its sides with the implied chisel).

falling_nodes.lua

@@ -4,9 +4,27 @@
 --   by hand, so shovels aren't really necessary.
 -- Setting crumbly = 2 for both, makes switching to shovels advantageous,
 --   at the cost of making stone even more difficult to work.
+--
+-- In addition, digging gravel now drops quarry:gravel, which doesn't drop flint.
+-- That way, player can't just keep redigging their gravel inventory to get more flints.
+-- 2020-06-13
 
 minetest.override_item("default:gravel", {
 	groups = {crumbly = 3, falling_node = 1},
+	drop = {
+		max_items = 1,
+		items = {
+			{items = {"default:flint"}, rarity = 16},
+			{items = {"quarry:gravel"}}
+		}
+	}
+})
+
+minetest.register_node("quarry:gravel", {
+	description = ("Gravel"),
+	tiles = {"quarry_gravel.png"},
+	groups = {crumbly = 3, falling_node = 1},
+	sounds = default.node_sound_gravel_defaults(),
 })
 
 -- Make dirt nodes also falling.