Split out NoteFSEntity into its own file

lib/core/note_folder.dart

@@ -1,27 +1,9 @@
 import 'dart:io';
 
-import 'package:gitjournal/core/note.dart';
 import 'package:path/path.dart';
 
-// FIXME: Maybe the parent should be a part of the Note, and the NoteFolder
+import 'note.dart';
-//        or maybe also a part of the NoteFolder
+import 'note_fs_entity.dart';
-class NoteFSEntity {
-  NoteFolder parent;
-  NoteFolder folder;
-  Note note;
-
-  NoteFSEntity(this.parent, {this.folder, this.note}) {
-    assert(folder != null || note != null);
-  }
-
-  bool get isNote {
-    return note != null;
-  }
-
-  bool get isFolder {
-    return folder != null;
-  }
-}
 
 class NoteFolder {
   List<NoteFSEntity> entities = [];

lib/core/note_fs_entity.dart

@@ -0,0 +1,22 @@
+import 'note.dart';
+import 'note_folder.dart';
+
+// FIXME: Maybe the parent should be a part of the Note, and the NoteFolder
+//        or maybe also a part of the NoteFolder
+class NoteFSEntity {
+  NoteFolder parent;
+  NoteFolder folder;
+  Note note;
+
+  NoteFSEntity(this.parent, {this.folder, this.note}) {
+    assert(folder != null || note != null);
+  }
+
+  bool get isNote {
+    return note != null;
+  }
+
+  bool get isFolder {
+    return folder != null;
+  }
+}