rename U-Boot-v2 project to barebox ...

This has been done with the following script:

find -path ./.git -prune -o -type f -print0 | xargs -0 -r sed -i \
	-e 's/u2boot/barebox/g' \
	-e 's/U2Boot/barebox/g' \
	-e 's/U-boot V2/barebox/g' \
	-e 's/u-boot v2/barebox/g' \
	-e 's/U-Boot V2/barebox/g' \
	-e 's/U-Boot-v2/barebox/g' \
	-e 's/U_BOOT/BAREBOX/g' \
	-e 's/UBOOT/BAREBOX/g' \
	-e 's/uboot/barebox/g' \
	-e 's/u-boot/barebox/g' \
	-e 's/u_boot/barebox/g' \
	-e 's/U-Boot/barebox/g' \
	-e 's/U-boot/barebox/g' \
	-e 's/U-BOOT/barebox/g'

find -path ./.git -prune -o \( -name "*u-boot*" -o -name "*uboot*" -o -name "*u_boot*" \) -print0 | \
	xargs -0 -r rename 's/u[-_]?boot/barebox/'

It needs some manual fixup following in the next patch

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

commands: remove maxargs ...

No need to check for maximum argument counts. The commands are
safe to be called with more arguments, so lets safe some bytes.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

commands: return COMMAND_ERROR_USAGE ...

instead of calling u_boot_cmd_usage in each command to safe
space.

Signed-off-by: Sascha Hauer <sha@pengutronix.de>

move several commands into extra files ...

move false, true, help, insmod, lsmod, version into extra files

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>