Updates issue #85 : XML files are equivalent to GRF in status - once saved as XML can save as XML by File/Save - menu item renamed
Removed Open from XML and added 'all graph files' filter for .grf and .xml
Save as dialog now has drop down filter for saving as .grf or .xml
Don't change name of document when adding a media file to a graph with existing name

git-svn-id: http://graph-studio-next.googlecode.com/svn/trunk@145 c2f33eb2-41b2-391d-4cb4-d9d0608729ba