Sanitize startup: if the instance does not exists default to the newly
added 'default' instance.

Removed the variable 'instance-name'.


git-svn-id: svn://localhost/emacslib/emacslib/trunk@415 a9598837-e506-0410-a967-fbf0066ee963
Renamed the function 'arv/get-instance-name' to
'arv/startup-get-instance-name'.


git-svn-id: svn://localhost/emacslib/emacslib/trunk@416 a9598837-e506-0410-a967-fbf0066ee963