History manager for remembering which projects have been opened.
An instance of this class is always available as the
The project history is used to enable the 'Reopen Project' menu.
Obtain a list of previously opened projects.
Returns an Array of
Clear all projects from the history.
Note: This is not a privacy function - other traces will still exist, e.g. window state.
Return a Promise that resolves when the history has been successfully cleared.