Add <QFileDialog> to GoldenCheetah.cpp

.. for QT5
DocumentMode and UnifiedTitleAndToolbar

.. don't go together, so removing the document mode update.
Update SaveDialogs for Tabbed Athletes

.. the save dialogs all assumed the current tab
   and current context were relevant when checking
   for unsaved files etc, but this was INCORRECT.

.. when window is closed each tab is checked IN TURN
   so the context should have been passed (because the
   current tab/context is just one of the many to save)
Refresh Popup on First Run

.. to give a visual cue as to what is happening, since it
   can feel like GC has 'hung' as it loads.

.. this is especially important now we open tabs in an
   existing mainwindow.

   The delay between clicking open and the tab appearring
   needs to have a visual indicator that something is
   actually happenning.
Add Close Button to Athlete Tab

.. so you can close athletes easily.
Mac MainWindow Crash Fixes

* refresh popup resize mainwindow crash
* tabbar button crash coz on left not right on Mac
merge upstream into master