#643

This is only used by the Editor. It was in common while the 
SanitizationService was used by the Player which then could display 
errors. Sanitization has been refactored and this is no longer needed.

Separating code changes is rather hard right now, so there is a lot of stuff that is part of this commit that should not. Details below.

- All elements have static fields that holds their title and icon. This way dynamic lists can be built (for example for delete dialog) which show title and icon for all elements. ALso icons and names can be changed in one place.
- Template-Tab has been added. This should have templates to help creating groups of ui elements. This is work in progress and there are actually no templates yet. So this will change or even be removed in the future. This is mostly UI, the code is "TODO".
- Refactoring and improvement for delete and reference dialogs
- Delete logic refactored for elements, sections and pages. There are no longer different dialogs when references are found, but instead one dialog that can do both.

Only works for a few commands (mainly page and section stuff).

- Adds new menu to page-bar, which shows issued change commands with a 
button to rollback the latest change.
- Added warning to the UI element that this is a experimental feature 
and can destroy units.
- Undo is done by having the normal function to apply the change to the 
unit-object and another to undo this change. The HistoryService manages 
the list and calling rollack (via UnitService).
- Further refactiring to the unit services.

#657

#635

Move element specific components to sub folder and just generally 
improve the file/component structure.

as this causes images to be displayed too small on iPads
when they are first loaded.

Mouuseenter, mouseleave for list and items are now always active and no 
longer added after the drag has started (they check of a drag operation 
is going on though). This makes the code simpler and more managable.

This reverts commit 8da0e95c.

Restrict maximun size of image.

#638

Helps to mark text on windows mobile, because the contextmenu hides the
handles bars of the selection

#634

#632

#631

This way it can be used for testing.

This helps accessibility in general and specifically allows testing for 
it.

#626

This fixes an issue where items could be added to only-one-item lists 
with replacement, when the  item to be replaced has the same list as 
origin.

#624

Fixed by using styles as in text field to define the background color

#625

#611

#609, #622, #601

#617

#611

#613

#611

#552

#621

#613