improve title page layout and extract natural language to separate file

template/utils.typ

@@ -1,8 +1,29 @@
-#let assert_in_dict(needle, dict, item_name) = {
-  if str(needle) not in dict {
+#let assert_in_arr(needle, arr, item_name) = {
+  if str(needle) not in arr {
     panic(
       "unknown " + item_name + " '" + str(needle) +
-      "', expected one of: " + dict.keys().map((k) => { "'" + str(k) + "'" }).join(", ")
+      "', expected one of: " + arr.map((k) => { "'" + str(k) + "'" }).join(", ")
     );
   }
 }
+
+#let assert_in_dict(needle, dict, item_name) = {
+  assert_in_arr(needle, dict.keys(), item_name);
+}
+
+#let is_none(thing) = {
+  if type(thing) == type(none) {
+    true
+  } else {
+    false
+  }
+}
+
+#let has_all_none(arr) = {
+  for item in arr {
+    if not is_none(item) {
+      return false;
+    }
+  }
+  true
+}