Bug 7017: Consolidate run_file into open_file_with_default_application

Also fix botched implementation in r22952, extract display_error function

git-svn-id: svn+ssh://svn.code.sf.net/p/gramps/code/branches/maintenance/gramps34@23002 4ae1f11a-8b86-4847-b8af-ab372f36d1fd
Fix some omissions in r23001

git-svn-id: svn+ssh://svn.code.sf.net/p/gramps/code/branches/maintenance/gramps34@23003 4ae1f11a-8b86-4847-b8af-ab372f36d1fd