Stop quitting deletion of closed projects

* Deleting closed projects is currently impossible due to a number of
  checks taking place that assume the project is open.

* Any attempt to use the API folder.members() results in an exception
  for a closed project. Need to avoid this and return a sane result

* RelateResourceFinder
* PreviewManager
* UdfManager
 * Checks the given resource is not a closed project. If it is then bail
   out with a sensible result

* VdbUiRefactorHandler
 * Check for closed project since getProjectFileResources also throws
   same exception as folder.members()

* RefactorResourceUtils
 * Modify check methods to sanely handle closed projects
 *


* PreviewManager
 *
TEIIDDES-1947: Creates factory method for groups with fill layout

* The overlapping group title issue exists not only for groups using grid
  layout but also those using fill layout.

* WidgetFactory
 * Factory method for creating a 'simple' group with fill layout with a
   margin height of 10 to workaround the overlapping content issue.

* Fixes the most common uses of this kind of group in the datatools
  connection UI dialogs.
Merge pull request #271 from phantomjinx/master

Stop quitting deletion of closed projects