feat: add gravel to craftable items

No longer need to stock gravel from external source, only cobblestone.

oregen-manager.lua

@@ -18,7 +18,8 @@ local KEEP_STOCKED = {
     ["create:zinc_nugget"] = 4 * 64,
     ["create:copper_nugget"] = 4 * 64,
     ["minecraft:netherrack"] = 4 * 64,
-    ["create:cinder_flour"] = 64,
+    ["create:cinder_flour"] = 0,
+    ["minecraft:gravel"] = 0,
 }
 
 local GLOBAL_LIMS = {
@@ -31,6 +32,10 @@ local LIMIT_EXCEPTIONS = {
         lower = 64,
         upper = 2 * 64,
     },
+    ["minecraft:gravel"] = {
+        lower = 10 * 64,
+        upper = 20 * 64,
+    },
 }
 
 -- if these exist, they will be used up
@@ -47,6 +52,12 @@ local PRODUCTS = {
 
 -- these will be crafted when needed
 local RECIPES = {
+    ["minecraft:gravel"] = {
+        ingredients = {
+            {"minecraft:cobblestone", 2 * 64},
+        },
+        addr = CRUSHER_ADDR,
+    },
     ["minecraft:iron_nugget"] = {
         ingredients = {
             {"minecraft:iron_nugget", 60},