undef21

Results 3 issues of undef21

* make tools independent from SDL; * add usage info in output; related issue: #5447

improvement

In the source root dir: ``` ln -s script/packaging/debian dpkg-buildpackage -us -uc -b ```

improvement
script

### Preliminary checks - [X] I've checked that there aren't [**other open issues**](https://github.com/ihhub/fheroes2/issues?q=is%3Aissue) on the same topic. - [X] I've checked that this issue is reproducible on the [**latest snapshot...

bug
ui