Import source file shouldn't allow to import to the same project

[Filippo]

When creating a project and then navigate to explore others project, you can import selected file to actual edited project.
This should be inhibited if source project is the same as the edited one.
The result right now are the creation of duplicated files (with a number append) so, not a big problem.
Still I'm putting it here just in case we run out of issues ;) to close.