Now resizing the surface when maximizing the Gantt Editor

  - Rewritten the ZoomController completely.
  - Disabled the ?dc=... value from Ext.Loader in order to allow
    for keeping break points.
  - Now using ganttBarPanel.StartDate instead of StartTime.

  Now showing a message if no tasks are defined yet

  Finally fixed milestone_p issue(?)

  Fixed issue with tasks with exactly equal start_date and end_date

  but at 00:00 and 23:59 respectively
- New tasks now by default take 8 hours to complete

  endDate of tasks are now scheduled at 23:59:59 of the day

- Refactored configuration code
- Created ConfigMenu class in sencha-core

  Fixed issue with end_date < start_date that leads to an error
  from the REST interface originally created by the database
  check-constraint. Now start_date <= end_date is enforced

  - Added CostCenter field
  - Added CostCenter model and store

  - Added read-only functionality and warnings

  (before, the last line was sometimes skipped)

  - Improved error message
  - Added remaining columns to GanttTreeStore (material)

  Now produces Beta warning when modifying the tree-model

  Saving the schedule now disables the Save button

- 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