-scm: always set SCM_REPOSITORY & require scm-git
Re-order exheres
Remove unused kernel forks
Add builtin command and function fix
Patch to remove menu border
Add base/syslinux-scm

The exlib is a bit hacky but it will do for now...
Add sys-kernel/linux configuration and key info

This is all very preliminary, and not even used by the current code.

I'm still to figure out how (or even if) to handle all this in Paludis...
exlibs/linux-kernel: major overhaul (once again)

- Use shipped configuration files instead of depending on the host system
  to provide them in some arbitrary location.

- Use systemd's kernel-install tool to generate and clean up initrd images
  and Boot Loader Specification entries in pkg_preinst/postrm. We give up
  a bit of control that we don't need anyway, and a lot of responsibility
  that we don't want.

- Miscellaneous clean- and fix-ups.
Remove base/syslinux and base category

Chances of me ever using SYSLINUX again are slim, unless I perhaps gain an
interest in network booting or something. Otherwise, I'll use UEFI or GRUB.