After loading a multipage/frame image, make all frames but the first invisible

This should prevent confusion when the frames are transparent (e.g.
animated GIFs), while still allowing the user to access all pages at
their leisure.
FreeImage: report save-time errors to the user

At load-time, PD automatically cascades to GDI+ to re-attempt loading.
At save-time, however, it's a "once or done" kind of thing.

Now, if FreeImage fails to save a given file, we will report whatever
captured error messages we receive to the user, and encourage them to
submit a bug report.
Additional clean-up checks for printer temp files

On Vista+, printing is handled via the system Print dialog.  This dialog
does not provide clean-up for any temp files it is passed, so we need to
do this manually upon program shutdown.