cad/netgen: Update to 6.2.2501 and improve.
- Actualise LICENSE to LGPL21 as in upstream
- Add patches to build with JPEG and MPEG
- Add WWW for source code repository
- Mark i386 as unsupported, as in upstream
- Replace explicit include dirs with localbase:ldflags
- Lint Makefile, sort entries for portclippy(1)
- Replace libav with ffmpeg as a MPEG dependency (see MOVED)
- Strip binaries and shared libraries in post-install phase.
- Change maintainer to alster@vinterdalen.se.
PR: 285491
Reported by: Älven <alster@vinterdalen.se>