Warn when skipping important items

[originalfoo]

If I've skipped something important in the skip.txt, it would be useful to see a warning on the loading screen (and also in the log file).

For example, in purple text: Warning: Skiped <asset id>

This would alert users that they've skipped something they probably shouldn't skip.

LSM could detect whether NExt2 mod is enabled so it could additionally warn about assets that NExt2 requires if NExt2 is active.

[thale5]

Would be useful but my LSM development activities are limited, at least for now.