Start rewrite of App(lication)View

The ApplicationView now uses a single TreeView to show all
Applications including the Modules used and the Blocks for each
Module.
Add TypecastingWidgetDataStore

This can be used to store data in SWT Widgets while making sure that
their type is correct.
Add logic for filling Application tree
Add logic for Update Button in Application
Add KillButtonActivator

Activates the kill button iff exactly one Application is selected
the Tree.
Things to be done:
* handle removal of Applications (Button stays activated for now)
* handle selection of multiple elements that all belong to the same
  application
Add functionality needed for kill button