#419 Should ask for new dir after cancelling overwriting of proj

[Charles N. Burns]

This is a minor glitch, but will (hopefully) be easy to
fix:

If you click on File --> New --> Project
and choose a project filename that already exists, it
asks the user if that file should be overwritten.
If the user chooses "no", the entire action of creating
a new project is cancelled. The expected behavior in
most apps that I have used which deal with files would
be to reopen the filename selection dialogue box to
allow the user to choose either a new directory, or a
new name for that project.