[Merge Request] q3map2 navmesh generation support from daemonmap

Hi, some time ago, navmesh generation was added to the now unmaintained daemonmap tool which is a q3map2 fork.

daemonmap was a tool used by Unvanquished mappers to build their maps. In fact, today the guideline is to use q3map2 (especially the @Ingar's build). But there is one thing daemonmap is still used for is navmesh generation. So today, Unvanquished mappers use q3map2 to compile maps, minimaps and lightmaps, but use daemonmap to generate navmeshes.

It could be very good to merge this navmesh support into q3map2 and get rid of daemonmap.