Return grouping extern crate to true by default

Author: nrc

src/config/mod.rs

@@ -69,7 +69,7 @@ create_config! {
 
     // Ordering
     reorder_extern_crates: bool, true, false, "Reorder extern crate statements alphabetically";
-    reorder_extern_crates_in_group: bool, false, false, "Reorder extern crate statements in group";
+    reorder_extern_crates_in_group: bool, true, false, "Reorder extern crate statements in group";
     reorder_imports: bool, true, false, "Reorder import statements alphabetically";
     reorder_imports_in_group: bool, true, false, "Reorder import statements in group";
     reorder_imported_names: bool, true, false,

tests/target/extern.rs

@@ -1,14 +1,17 @@
 // rustfmt-normalize_comments: true
 
-extern crate bar;
-extern crate chrono;
-extern crate dotenv;
-extern crate foo;
 extern crate foo;
 extern crate foo as bar;
+
+extern crate chrono;
+extern crate dotenv;
 extern crate futures;
-extern crate proc_macro;
+
+extern crate bar;
+extern crate foo;
+
 // #2315
+extern crate proc_macro;
 extern crate proc_macro2;
 
 extern "C" {