Decide which boot addons should be still shipped with Grml 2020+ ISOs

[mika]

While refreshing the grml-live-grml Debian source package (which builds the grml-live-addons Debian binary package), I noticed that we have several boot addons that are pretty much unmaintained nowadays.

Especially the bsd4grml (4.8MB), balder10.imz (1.2MB, FreeDOS based, see https://www.finnix.org/Balder) + allinone.img (1.5MB, see http://schierlm.users.sourceforge.net/bootdisk/index.html) are among the ones I tend to drop with the upcoming Grml release.

If anyone objects or has further suggestions, please let me/us know!

[mika]

Feedback from @schierlm, asking him what's his take on his allinone.img usage for Grml:

probably not... gPXE and Grub are also available separately, so is hdt. And stuff like sbm or plop are no longer needed either, now that every machine can boot from USB...