6821: CLI asks forever when trying to overwrite while exporting


git-svn-id: svn+ssh://svn.code.sf.net/p/gramps/code/trunk@22542 4ae1f11a-8b86-4847-b8af-ab372f36d1fd
0006352: Bookmarking a source in the citation tree creates a blank bookmark. Disallow bookmarking a source in the Citation Tree View, and do not add sources to the history in the Citation Tree View.

git-svn-id: svn+ssh://svn.code.sf.net/p/gramps/code/trunk@22545 4ae1f11a-8b86-4847-b8af-ab372f36d1fd