Add stacktrace to ParseError

Fixes #854. Also clean up the parse error test a little, while adding a .stack check.
QUnit. The results are collapsed if there is no error. Try to expand the results of one test. E.g. for test # 627 you will see:
```
<p> element has already been removed from the DOM
promise was fulfilled before transition had completed
<p> element should have been removed from the DOM
```