Fix issue #216 : Added auto-size button to property dialog
auto size off by default and is persisted in preferences, .
When auto size is enabled showing or switching property pages resizes the property dialog to fit the property page (the old behaviour)
When auto size is off showing or switching property pages only resizes if needed to fit the property page
New property dialogs are shown at the same size of the last closed property dialog - not persisted.

git-svn-id: http://graph-studio-next.googlecode.com/svn/trunk@315 c2f33eb2-41b2-391d-4cb4-d9d0608729ba