Now that the dependeny to the main window is removed from the
DBBrowserDB class we can get rid of all the dialogs and widget related
stuff in the cmake file used for the unit test project. Because our
Application class depends on the main window, too, the code for the CSV
tests is changed to use Qt's standard QApplication class.
Add a new test class for testing the import functionality. Currently
it's only covers some test cases for the CSV import.
Since the function to test here (DBBrowserDB::decodeCSV) is part of the
DBBrowserDB class, that class has a reference to the main window and the
main window basically depends on the entire rest of the project the
makefile grew quite a bit unfortunately.
