Update title of panel via double clicking

[ppf2]

Would be nice for the end user to be able to double click on the title of a panel to quickly change the title value (in place edit) without having to go into edit mode.

[rashidkpc]

As dashboard panels are now saved objects we don't want to let the user believe they are only changing the title for that one panel on one dashboard, when really it would update every dashboard the panel is used on.