Increase the top layout count for combination attempts

src/combine-layouts.rs

@@ -23,7 +23,7 @@ fn main() {
     let transposed_city = transpose_city(&city);
     eprintln!("Finished building a transposed city");
 
-    const TOP_LAYOUT_COUNT: usize = 1000;
+    const TOP_LAYOUT_COUNT: usize = 1500;
 
     let mut cache = combine::CompatibilityCache::new();