Regenerate protos and update protobuf constraint

Improves/changes the regeneration script:
* Use the protoc_plugin from the pubspec.yaml - so the constraint is
  fixed
* Move it to `tool/` for better discovery.
* Mention in `README.md` for better discovery.
* Clone into `tmp/` so we don't have to redownload everything
* Compile all protos in one command (much faster)
* Use `dart format` instead of `dartfmt` (actually works on modern SDK).

Prepares for a new publication.

.gitignore

@@ -2,3 +2,4 @@
 .packages
 .pub/
 pubspec.lock
+tmp/

CHANGELOG.md

@@ -1,3 +1,6 @@
+## 0.13.8
+ * Require `package:protobuf` ^3.1.0.
+
 ## 0.13.7
  * Widen dependency constraint on `package:http`.
 

README.md

@@ -166,3 +166,8 @@ This will perform a remote docker build in the cloud and deploy a new version.
 You can find the URL to the version that got deployed
 in the output of `gcloud app deploy` (as well as via the
 [Cloud Console](https://console.cloud.google.com) under `AppEngine > Versions`).
+
+## Regenerating protobuf
+
+You need to have protoc in `$PATH`.
+Run the `tool/fetch_protos_and_regenerate_dart.sh` script. It will fetch the latest protos and compile them for dart using the protoc_plugin in `dev_dependencies`.

lib/src/grpc_api/dart/google/api/annotations.pb.dart

@@ -1,29 +1,33 @@
-///
+//
 //  Generated code. Do not modify.
 //  source: google/api/annotations.proto
 //
 // @dart = 2.12
-// ignore_for_file: annotate_overrides,camel_case_types,unnecessary_const,non_constant_identifier_names,library_prefixes,unused_import,unused_shown_name,return_of_invalid_type,unnecessary_this,prefer_final_fields
+
+// ignore_for_file: annotate_overrides, camel_case_types, comment_references
+// ignore_for_file: constant_identifier_names, library_prefixes
+// ignore_for_file: non_constant_identifier_names, prefer_final_fields
+// ignore_for_file: unnecessary_import, unnecessary_this, unused_import
 
 import 'dart:core' as $core;
 
 import 'package:protobuf/protobuf.dart' as $pb;
 
-import 'http.pb.dart' as $0;
+import 'http.pb.dart' as $55;
 
 class Annotations {
-  static final http = $pb.Extension<$0.HttpRule>(
-      const $core.bool.fromEnvironment('protobuf.omit_message_names')
-          ? ''
-          : 'google.protobuf.MethodOptions',
-      const $core.bool.fromEnvironment('protobuf.omit_field_names')
-          ? ''
-          : 'http',
+  static final http = $pb.Extension<$55.HttpRule>(
+      _omitMessageNames ? '' : 'google.protobuf.MethodOptions',
+      _omitFieldNames ? '' : 'http',
       72295728,
       $pb.PbFieldType.OM,
-      defaultOrMaker: $0.HttpRule.getDefault,
-      subBuilder: $0.HttpRule.create);
+      defaultOrMaker: $55.HttpRule.getDefault,
+      subBuilder: $55.HttpRule.create);
   static void registerAllExtensions($pb.ExtensionRegistry registry) {
     registry.add(http);
   }
 }
+
+const _omitFieldNames = $core.bool.fromEnvironment('protobuf.omit_field_names');
+const _omitMessageNames =
+    $core.bool.fromEnvironment('protobuf.omit_message_names');

lib/src/grpc_api/dart/google/api/annotations.pbenum.dart

@@ -1,6 +1,10 @@
-///
+//
 //  Generated code. Do not modify.
 //  source: google/api/annotations.proto
 //
 // @dart = 2.12
-// ignore_for_file: annotate_overrides,camel_case_types,unnecessary_const,non_constant_identifier_names,library_prefixes,unused_import,unused_shown_name,return_of_invalid_type,unnecessary_this,prefer_final_fields
+
+// ignore_for_file: annotate_overrides, camel_case_types, comment_references
+// ignore_for_file: constant_identifier_names, library_prefixes
+// ignore_for_file: non_constant_identifier_names, prefer_final_fields
+// ignore_for_file: unnecessary_import, unnecessary_this, unused_import

lib/src/grpc_api/dart/google/api/annotations.pbjson.dart

@@ -1,10 +1,14 @@
-///
+//
 //  Generated code. Do not modify.
 //  source: google/api/annotations.proto
 //
 // @dart = 2.12
-// ignore_for_file: annotate_overrides,camel_case_types,unnecessary_const,non_constant_identifier_names,library_prefixes,unused_import,unused_shown_name,return_of_invalid_type,unnecessary_this,prefer_final_fields,deprecated_member_use_from_same_package
 
-import 'dart:core' as $core;
+// ignore_for_file: annotate_overrides, camel_case_types, comment_references
+// ignore_for_file: constant_identifier_names, library_prefixes
+// ignore_for_file: non_constant_identifier_names, prefer_final_fields
+// ignore_for_file: unnecessary_import, unnecessary_this, unused_import
+
 import 'dart:convert' as $convert;
+import 'dart:core' as $core;
 import 'dart:typed_data' as $typed_data;