Merge: Nitcatalog for nitpm

This move the packages fetched by nitpm to nitlanguage.org and use the nitcatalog infrastructure to publish and update the ini files.

The list of public packages is now in `contrig/nitpm_packages.txt` (was `oot.txt`) and new public packages can be added to the file trough PR and review by the community.

Note that there is nothing yet to check the sanity of public pagkage (nor do any long run quality assurance).

Pull-Request: #2650
Reviewed-by: Alexis Laferrière <alexis.laf@xymus.net>