fill_config.py: sort foreach items numerically, not alphabetically

Make sure that BTS 11 doesn't get sorted between BTS 1 and 2, because osmo-bsc
requires the BTS to be configured in numerical order.

Also makes sense as foreach loop ordering in general.

Change-Id: Ib06052fd71def3d4c869ee9b3dc4d02ba06267af
diff --git a/net/fill_config.py b/net/fill_config.py
index d99d9f6..557381f 100755
--- a/net/fill_config.py
+++ b/net/fill_config.py
@@ -166,19 +166,19 @@
       item_m = item_re.match(item)
       if not item_m:
         continue
-      items.add((item_m.group(1), item_m.group(2)))
+      items.add((int(item_m.group(2)), item_m.group(1)))
 
     items = sorted(list(items))
 
     expanded = [before_block]
-    for item, nr in items:
+    for nr, item in items:
       expanded_block = foreach_block
 
       while True:
         expanded_block_was = expanded_block
 
         expanded_block = expanded_block.replace('${%sn_' % arg, '${%s_' % item)
-        expanded_block = expanded_block.replace('${%sn}' % arg, nr)
+        expanded_block = expanded_block.replace('${%sn}' % arg, str(nr))
         expanded_block = replace_vars(expanded_block, tmpl_dir, tmpl_src, local_config)
 
         if expanded_block_was == expanded_block: