Fix some webdev/ng issues, decoupling fixed pages from TS version (#298)

* Update structural-directives, decouple from TS version

Fixes #292

* structural-directives tweaks

* Update pipes, decouple from TS version

The main diffs:

```
< It must be a valid JavaScript identifier.
---
> It must be a valid Dart identifier.
…
< runs after every JavaScript event:
---
> runs after every DOM event:
```

Fixes #291

* Update component-styles, decouple from TS

The only semi-interesting diffs:

<   quest-summary.component.ts
<   quest-summary.component.html
<   quest-summary.component.css
---
>   quest_summary_component.dart
>   quest_summary_component.html
>   quest_summary_component.css

Fixed #289.

* Uncouple template-syntax

* Make double curlies reappear

* fix #287, remove cached TS source

Author: kwalrath