Restored missing icons for menus.

Gnome stock icons are not available in GTK# for Windows. Added new 16x16 icons as resources for the menus whose icons went missing.

PersonaAddEditor: added a frame around the Notes textview; it was unperceptible under the Windows theme otherwise.
Add titles to modal message dialogs.

Modal dialogs in Gnome 3 don't have a window title, but in Windows they do and it looks weird for their title to be empty.