- Fixed the display of resources behind a sprite

  - Added drag-and-drop configuration to all sprites,
    in order to allow them to act as source and target
    for dependencies
  - Fixed issue with negative width in percent-bars

  - Moved MS-Project Warning portlet to the bottom of the project page
  - Added "ReadOnly" configuration option to GanttEditor
  - Fixed GanttTreePanelController log messages
  - Fixed issue with "chain" icon not appearing in GanttEditor
  - Fixed issue with different "icons" per task after loading
  - Fixed issue with icon not changing after setting a task to milestone_p

  - Moved functionality to PO.Utilities.reportError()
  - Eliminated duplicate code from GanttButtonController

  function in the GanttBarPanel, where it also
  handles the restore of the zoom configuration

  - Now all scrolling is handled in the GanttZoomController
  - Focussing on a project includes a zoom on the center of
    the visible area
  - Both scroll and axis start- and end-dates are now persistent
    using preferences

  This is now all handled in the GanttZoomController.
- Fixed bug with loading preferences and moved preference
  functionality into the SenchaPreferenceStore

  from GanttZoomPanel to GanttBarPanel, where both
  the needsRedraw variable and the redraw() function
  are located.

  Now redrawing only if the needsRedraw variable is set to true

- ToDo: Factor error reporting out into a sencha-core functionality

  Now showing an error message instead of a blank screen if
  executed in a tab in a non-Gantt project

  indicating the type of object (task, project, ticket, ...)

  after setting milestone property in task
  property panel

  Fixed various issues

  Implemented aggregation of planned_units towards the root of the project tree

  Fixed issue creating a new task with empty project_nr.
  The project_nr is now assigned by the client side

  Fixed issue creating dependency from task to itself

  Fixed condition for the color of dependencies

  Fixed issue deleting a second dependency.

  Moved GanttButtonController to separate file