refactor: re-layput project

- move assets (raw jsons, icons, meshes and i18n data) into the root of repo.
- move script into the root of repo.
- modify blender manifest according to this changes.
- optimize gitignore.

scripts/extract_json.py

@@ -0,0 +1,6 @@
+import common
+
+
+
+if __name__ == '__main__':
+    common.setup_logging()