gfxpayload support
* commands/videotest.c (grub_cmd_videotest): use grub_video_set_mode
* include/grub/video.h (GRUB_VIDEO_MODE_TYPE_PURE_TEXT): new definition
(grub_video_setup): remove
(grub_video_set_mode): new prototype
* loader/i386/linux.c (DEFAULT_VIDEO_MODE): new definition
(vid_mode): remove
(linux_vesafb_res): compile only on PCBIOS
(grub_linux_boot): support gfxpayload
* loader/i386/pc/xnu.c (video_hook): new function
(grub_xnu_set_video): support gfxpayload
* term/gfxterm.c (DEFAULT_VIDEO_WIDTH): removed
(DEFAULT_VIDEO_HEIGHT): likewise
(DEFAULT_VIDEO_FLAGS): likewise
(DEFAULT_VIDEO_MODE): new definition
(video_hook): new function
(grub_gfxterm_init): use grub_video_set_mode
* util/grub.d/30_os-prober.in: remove explicit modesetting before
loading xnu
* video/video.c (grub_video_setup): removed
(grub_video_set_mode): new function based on grub_gfxterm_init and
grub_video_setup
* util/update-grub_lib.in: Copy to ...
* util/grub-mkconfig_lib.in: ... this. Update all users.
* util/update-grub_lib.in: Make it a stub to `grub-mkconfigig_lib.in'.
* util/update-grub.in: Rename to ...
* util/grub-mkconfig.in: ... this. Update all users. Remove `-y'
option. Add `--output' option to allow users to specify the generated
configuration file. Default to stdout.
(update_grub_dir): Rename to ...
(grub_mkconfig_dir): ... this.
(grub_cfg): Default to an empty string.
* conf/common.rmk (update-grub): Rename to ...
(grub-mkconfig): ... this.
(update-grub_lib): Copy to ...
(grub-mkconfig_lib): ... this.
(update-grub_SCRIPTS): Copy to ...
(grub-mkconfig_SCRIPTS): ... this. Update all users.
(update-grub_DATA): Rename to ...
(grub-mkconfig_DATA): ... this.
* util/grub.d/30_os-prober.in: New script. Use `os-prober' and
`linux-boot-prober' (if installed) to detect other operating
systems which are installed on the computer and add them to
the boot menu.
* conf/common.rmk: Build and install 30_os-prober.
