* In that way, we have unified directory scheme among {pxe,sys,ext,iso}linux,
  sharing the same directory structure and config files.
* Also enable IPAPPEND (will show a warning message about unknown directive in non-pxelinux before menu)

NEW:
* Rename syslinux*.cfg -> archiso*.cfg
* Now syslinux.cfg is only a "loadconfig" trick like we are doing for isolinux
* All paths are now relative to %INSTALL_DIR% ($archisobasedir) (Default: /arch/)

Signed-off-by: Gerardo Exequiel Pozzi <vmlinuz386@yahoo.com.ar>