Lots of improvements

main changes: drop rootfs-skeleton, cleanup xwin
builders now supports building from "updates" repo (ie, use latest packages where available) - if the correct repo is specified.
add mick's 64-bit slacko binaries (not tested yet)
rc.sysinit: don't use mingetty, use autologin directly instead
fixmenus uses jwm_menu_create when available
slackware now boots to graphical desktop