Merge: app.nit: fix issues in examples and calculator

- Fix missing Makefile dependencies by correctly using the -m options in calls to nitls. It would work without the -m for simple programs but misses some files when there are conditional importations.
- Fix crash in `http_request_example` by updating the latest app.nit UI API from #2547. Closes #2577.
- Compile the scientific desktop variant of the calculator with the `all` rule.

Pull-Request: #2579