Create initial release script

scripts/release.dart

@@ -0,0 +1,57 @@
+import 'dart:io';
+
+Future<void> main(List<String> args) async {
+  if (args.isEmpty || !{'patch', 'minor', 'major'}.contains(args[0])) {
+    print('Unknown version bump type');
+    exit(1);
+  }
+
+  final pubspecFile = File('pubspec.yaml');
+  final pubspecContents = await pubspecFile.readAsString();
+
+  final versionMatch = RegExp(r'version: (\d+)\.(\d+)\.(\d+)\+(\d+)')
+      .firstMatch(pubspecContents);
+
+  var major = int.parse(versionMatch.group(1));
+  var minor = int.parse(versionMatch.group(2));
+  var patch = int.parse(versionMatch.group(3));
+  var code = int.parse(versionMatch.group(4));
+
+  switch (args[0]) {
+    case 'patch':
+      patch++;
+      break;
+    case 'minor':
+      patch = 0;
+      minor++;
+      break;
+    case 'major':
+      patch = 0;
+      minor = 0;
+      major++;
+      break;
+  }
+  code++;
+
+  final newVersion = '$major.$minor.$patch+$code';
+
+  confirm('Version looks good? $newVersion');
+
+  final updatedPubspec = pubspecContents.replaceFirst(
+      versionMatch.group(0), 'version: $newVersion');
+
+  await pubspecFile.writeAsString(updatedPubspec);
+}
+
+void confirm(String message) {
+  print('$message [y/n]');
+
+  switch (stdin.readLineSync()) {
+    case 'y':
+    case 'yes':
+      break;
+    default:
+      print('Exiting');
+      exit(1);
+  }
+}