Opens a database from a file. The user is prompted to
save any unsaved changes of the current database.
The file name extension of CADEMIA documents is cademia. It is,
however, possible to use an arbitrary file name extension. This feature
allows the user to load older CADEMIA documents with file extension cib
(CAD in der Bauinformatik).
The command uses a modeless file dialog. It should be noted that user
interaction can also take place via the command line dialog. This enables
the user to fully describe user interaction in command macros.