Save user customization of editor

The assumption is that a users will tailor their working environment to their display setup and preferences and that they would like to keep that setting.

The following changes to the editor should be persistant on a user level:

• Showing and hiding of colums
• Order of columns
• Width of columns
• Showing / Hiding of 
  • left panel (files / reference files)
  • right panel (segment meta data / comments)
• Which area in the left or right panel is currently shown
  • left panel: files or reference files
  • right panel: segment meta data or comments
• The font-size and the visualReview layout size

The existing editor modes stay, as they are. Yet if the editor working environment is customized for the current user, a view mode "Customized" is added and shown as selected. As soon as the user selects one of the default view modes, the "Customized" view mode button will not be shown anymore.

In "Simple mode" a new button "Reset layout" is introduced, that is only shown, if the working environment is customized. It resets the layout to "Simple mode".