Bootable GRUB2 disk image with ext2 partition

This provides bootable disk images for x86 platforms via

! RUN_OPT="--target disk"

The resulting disk image contains one ext2 partition with binaries from
the GRUB2 boot loader and the run scenario. The default disk size fits
all binaries, but is configurable via

! --disk-size <size in MiB>

in RUN_OPT.

The feature depends on an grub2-head.img, which is part of the commit,
but may also be generated by executing tool/create_grub2. The script
generates a disk image prepared for one partition, which contains files
for GRUB2. All image preparation steps that need superuser privileges
are conducted by this script.

The final step of writing the entire image to a disk must be executed
later by

  sudo dd if=<image file> of=<device> bs=8M conv=fsync

Fixes #1203.
Start the ACPI driver in Qt5 run scripts if needed

Fixes #1219.
dde_ipxe: add Intel I217-LM PCI ID

Fixes #1220.
Qt launchpad: coding style fixes

Fixes #1221.
Qt launchpad: use XML configuration

With this patch, Qt launchpad entries are configured the same way as with
the Scout launchpad.

Fixes #1222.
Qt5: fix menu problems

- fix sub menu positioning
- disable window decoration for popup menus

Fixes #1226.
fb_drv: fix clipping

Use the clipped coordinates for calculating the buffer addresses, too.

Fixes #1227.
fb_drv: implement 'buffered' mode for OMAP4

Fixes #1228.
Qt5: use double buffering

Fixes #1229.
nitpicker: load initial config before announcement

This patch fixes a potential race condition that could happen if a
client connects to nitpicker before the signal for the import of the
initial configuration was delivered. In this case, nitpicker would be
unable to assign a domain to the session (because this information comes
from the configuration), rendering subsequent calls to 'mode' invalid.
The patch solves this problem by manually calling the signal handler
for importing the configuration.
os: add RGB888 pixel format
wm: remove debug messages
gems: new backdrop application

The new backdrop found at gems/src/app/backdrop replaces the old program
that was hosted in the demo repository.
terminal_log: don't write null-termination to terminal

Fixes #1231.
Qt5: migrate to new ports mechanism

Fixes #1233.
GCC: migrate to new ports mechanism

Fixes #1234.
GBD: migrate to new ports mechanism

Fixes #1237.
wm: fix WHEEL event translation

Fixes #1242.
vfs: add vfs handle header to single_file header

Fixes #1238.
vfs: add Rtc_file_system

The Rtc_file_system reads the current time from a Rtc_session and
provides the time as '%Y-%m-%d %H:%M\n' to all users of the vfs
node.

Fixes #1238.