Fix issue #174 : New menu option File/File Options/Always save GRF and XML. Enabled by default
If enabled, all file save/save as operations save both GRF and XMl files with extensions changed where necessary.

git-svn-id: http://graph-studio-next.googlecode.com/svn/trunk@281 c2f33eb2-41b2-391d-4cb4-d9d0608729ba