Move the Editor and Eclipse plugins over to using stagehand for the new project templates.

Move the Editor and Eclipse plugins over to using stagehand for the new project templates.

R=danrubel@google.com, pquitslund@google.com, scheglov@google.com

Committed: https://code.google.com/p/dart/source/detail?r=41339

[devoncarew, 2014-10-24 20:50:19]

devoncarew@google.com changed reviewers:
+ danrubel@google.com, scheglov@google.com

[devoncarew, 2014-10-24 20:50:20]

Move the Editor and the Eclipse plugins over to using Stagehand for the new
project wizard (https://github.com/google/stagehand).

- install stagehand on demand, use it to populate the list of project types in
the dart new project wizard
- add a progress bar to the editor and plugins wizards
- populate the list of available samples asynchronously (the very first request
can be expensive)
- improve the look and layout of the project wizards
- use a styled label provider for the project template names

[scheglov, 2014-10-24 21:00:05]

LGTM

[pquitslund, 2014-10-24 22:34:30]

pquitslund@google.com changed reviewers:
+ pquitslund@google.com

[pquitslund, 2014-10-24 22:34:31]

LGTM!

[danrubel, 2014-10-27 01:35:17]

Sweet! LGTM

[devoncarew, 2014-10-27 21:00:02]

Committed patchset #2 (id:20001) manually as r41339 (presubmit successful).