import/load of files should be separate from project creation #497
Description
Original report by Joern Ungermann (Bitbucket: joernu76, GitHub: joernu76).
One might need to update a project after exporting it and working on it in a separate tool by importing it again.
So we need a load/import feature for existing projects.
For non-empty projects a warning message box should be displayed.
The init with existing file feature might then be removed.