Extract a class 'ModelContainer'.
Save changes of the modifications to annotations.json.
Add presentation handlers to edit modifications.
Add commands to edit modifications to the commad.factory.
Re-render entity or relation if modifications are changed.
Implemente presenter.
Update modification buttons after modifications are changed.
Bugfix entities changed was show as is not selected.
Bugfix a parameter of command.factory.entityCreateCommand was not fixed when entities is pasted.
Bugfix a parameter of factory.entityCreateCommand was not fixed when a span is moved;
Merge pull request #108 from pubannotation/edit_modification

Edit modification