This removes a few popup advice functions that are no longer necessary
and changes how we handle org agenda windows (they're now displayed in
the current window, rather than a popup -- see org-agenda-window-setup
to change this).
Other issues addressed:
+ Fixes 'Attempt to delete main window of frame' errors when using
org-todo from popups (particularly in daemon Emacs).
+ Removed the custom 'popup-window options for org-agenda-window-setup
and org-src-window-setup, and change them to 'current-window and
'other-window, respectively.
6f6e30c428