run GomuksInit on an Isolate

Fixes #70

lib/controllers/client.dart

@@ -49,15 +49,17 @@ import "package:path_provider/path_provider.dart";
 class ClientController extends AsyncNotifier<int> {
   @override
   Future<int> build() async {
-    final Pointer<Char> root;
-    if (Platform.isAndroid || Platform.isIOS) {
-      final dir = await getApplicationSupportDirectory();
-      root = "${dir.path}/gomuks".toNativeUtf8().cast();
-    } else {
-      root = nullptr.cast();
-    }
+    final handle = await Isolate.run(() async {
+      final Pointer<Char> root;
+      if (Platform.isAndroid || Platform.isIOS) {
+        final dir = await getApplicationSupportDirectory();
+        root = "${dir.path}/gomuks".toNativeUtf8().cast();
+      } else {
+        root = nullptr.cast();
+      }
 
-    final handle = GomuksInit(root);
+      return GomuksInit(root);
+    });
 
     final callable =
         NativeCallable<

scripts/generate.dart

@@ -11,12 +11,12 @@ void main(List<String> args) async {
 
   final libclangPath = Platform.environment["LIBCLANG_PATH"];
   FfiGenerator(
-    output: Output(
+    output: .new(
       dart: .new(
         path: Platform.script.resolve("../lib/src/third_party/gomuks.g.dart"),
       ),
     ),
-    visitors: [Visitor(func: (node) => node.isIncluded = true)],
+    visitors: [.new(func: (node) => node.isIncluded = true)],
     input: .new(
       entryPoints: [File(join(repoDir.path, "pkg", "ffi", "gomuksffi.h")).uri],
       compilerOptions: [