Save favourite queries

[gomoripeti]

Keep a list of favourite queries in the backend.
(Advantage is that it can be shared among users, but can only be shared among multiple target nodes in case of a setup with a separate common xprof gui node.)

Backend

• Responsibility of xprof_gui (as opposed to xprof_core)
• Have to be persisted to a file to survive xprof_gui application restarts
• File format should be human readable and editable (eg erlang term format)
• File location configurable with app env (with sensible default)
• Allow loading multiple files (could be done in second iteration)

Frontend

• Each graph (monitored function) should have a button (star) to add it to favourites
• Find a way to list favourite queries (open to discussion). Would be nice if it would fit in style to the current Query textbox/Autocomplete scheme (eg with some key-binding, star button or menu item list all favourites in the suggestion dropdown list and allow filtering based on text in query text box)