Release v4.12-1: First release with binary packages

This release includes:
- APK package for Alpine Linux (x86_64)
- DEB package for Debian/Ubuntu (amd64)
- Source tarball from gpl-release/
- SHA256 checksums for verification

Binary packages are now available on the GitHub Releases page.
Users can download pre-built packages or build from source.

No code changes from v4.12, this is a packaging release.

Modernization (#5)

* Increase NTOTAL nations from 25 to 35 so there is capacity for everyone

* Modernization of Makefile, header.c, main.c

* Mark this release as 4.12, updating the copyrights in copyscreen and credits to highlight this is a GPL v3 version

Conquer v4.11, from usenet, last official version.

Changed PATCHLEVEL to a string and updated to 4.11a to denote minor d…

…eviation

Conquer v4.10, from usenet

Conquer v4.09, from usenet

Conquer v4.08, from usenet

Conquer v4.07, from usenet

Conquer v4.06, from usenet

Conquer v4.05, from usenet