hopefully fix mapping stack III

provide neoforge with a version of custom_mappings.tiny from intermediary->named, instead of official->[intermediary, named]

custom_mappings_strip.py

@@ -0,0 +1,21 @@
+#!/bin/python3
+
+input_file = "custom_mappings.tiny"
+output_file = "custom_mappings_stripped.tiny"
+
+with open(input_file, "r") as f:
+    lines = f.readlines()
+
+with open(output_file, "w") as f:
+    for line in lines:
+        stripped = line.rstrip("\n")
+        leading_tabs = len(stripped) - len(stripped.lstrip("\t"))
+        parts = stripped.lstrip("\t").split("\t")
+
+        if len(parts) < 2:
+            f.write(line)
+            continue
+
+        # remove third-to-last column (i.e. 'official')
+        new_parts = parts[:-3] + parts[-2:]
+        f.write(("\t" * leading_tabs) + "\t".join(new_parts) + "\n")