* toh-6: trim spaces from cache file to simplify diff
* toh-6: copy latest over cache before editing latest
* docs(toh-6): post-RC5 Dart resync and TS fixes
Contributes to #2077.
TS-side changes include:
- Merged three versions of `app/app.module{,1,2}.ts` into a single file
and used docregions instead.
- Misnamed files:
- `rxjs-operators.ts` -> `rxjs-extensions.ts`
- `hero-search.service.html` -> `hero-search.component.html`
- Fixed BAD FILENAME error.
Lint reports no errors and toh-6 e2e tests pass.
