games/openomf: Update 0.6.5 => 0.8.3, improve port

Changelogs:
https://github.com/omf2097/openomf/releases/tag/0.7.0
https://github.com/omf2097/openomf/releases/tag/0.7.1
https://github.com/omf2097/openomf/releases/tag/0.8.0
https://github.com/omf2097/openomf/releases/tag/0.8.1-rc2
https://github.com/omf2097/openomf/releases/tag/0.8.1-rc3
https://github.com/omf2097/openomf/releases/tag/0.8.1
https://github.com/omf2097/openomf/releases/tag/0.8.2
https://github.com/omf2097/openomf/releases/tag/0.8.3-fk1
https://github.com/omf2097/openomf/releases/tag/0.8.3

Improve port:

• Add github to WWW.
• Add LICENSE.
• Switch to default cmake build instead of cmake:insource.
• Parapetrize "openomf" with "${PORTNAME}" in several places.
• Fix warnings from portclippy and portlint.

PR: 289093
Co-authored-by: Vladimir Druzenko <vvd@FreeBSD.org>