Renaming documents and objects

The following improvements are required:

1. It should be possible to rename a document without creating a copy by using "F2" or the "Rename" item in the context menu.
The "Rename" item should be available for a document (if it is not locked), for a sequence objects (if the document is not locked), etc. It should be disabled for objects that do not allow renaming (e.g. annotation objects).

2. When a sequence is renamed the Circular View should be updated automatically (the sequence name is displayed at the center of the Circular View).