Fixes bug 454227:
- a new Job is spawned for LanguageSpecificURIEditorOpener.selectAndReveal(..) so it doesn't block the UI
- added a marker interface IOutlineTreeProvider.Background and added it to XtendOutlineTreeProvider so the Xtend outline page is updated in the background
- added forceReconcile() to XtextEditor.createPartControl(..) to avoid conflicts during initialization of the outline view
- updated two tests that previously relied on the Xtend editor to update its state immediately after opening

Change-Id: I0a52f726852508f411a902123f3940c8690610be
Signed-off-by: Miro Spönemann <miro.spoenemann@itemis.de>
Merge "Fixes bug 454227: - a new Job is spawned for LanguageSpecificURIEditorOpener.selectAndReveal(..) so it doesn't block the UI - added a marker interface IOutlineTreeProvider.Background and added it to XtendOutlineTreeProvider so the Xtend outline page is updated in the background - added forceReconcile() to XtextEditor.createPartControl(..) to avoid conflicts during initialization of the outline view - updated two tests that previously relied on the Xtend editor to update its state immediately after opening"