Delete posts, don't reject them

- Use DelPost not Review(approval = None)
- Add Post and PostState.lastManuallyApprovedById
- Get rid of some deprecated functions, use review2() and
  doSomethingWithPost2() instead.
Fix test suite compilation error.
Change ReviewPost(Option[Approval]) to ApprovePost(Approval).
Rename some ...review... to ...approve... .
Merge branch 'topic-delete-dont-reject' into topic-functional-flags.
Make CancelAllOnFirstFailure work with this newer version of ScalaTest.
Make eventually() abort if browser window closed.
Remove broken definitely-typed submodule.
Add definitely-typed again.
Remove unused module angular.dart.ui.
Use https Git URL not git@, for debiki-bootstrap-stylus.
Add missing JS dependency, remove unneeded, fix homepage link.
Merge branch 'topic-build-on-other-machines'.
Merge branch 'master' into topic-functional-flags.
Add ModerationSpec E2E test

And:
- Add classes to moderation.html buttons so E2E tests find them
- Don't use jQuery UI Dialog's buttons in flag form, they don't work
  with E2E tests, cannot find them. Instead use my own buttons.
Add no-action-buttons test, fails.
Use TestVoter, delete TestRater.
Make delete flagged post clear flags

This fixes ModerationSpec but it breaks later anyway when clicking
'Go back to site'.