…map#3585)
Right now, every time Colmap is restarted, all file dialogs start from
the default location. This forces the user to browse back to the project
or dataset folder again and again, which is annoying.
This PR changes that behavior by using Qt QSettings to store the
last-used directory for each dialog (open, save, import, export, etc.),
with a global fallback. That way, the next time a dialog is opened it
will point to the folder the user was previously working in.
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Co-authored-by: Johannes Schönberger <jsch@demuc.de>