Add new command to allow obdctl usage from command-line.

Add new command to allow obdctl usage from command-line.
usage: --device <devno> <command [args ...]>

This is exactly the same thing as:
	obdctl <<- EOF
	device <devno>
	connect
	command [args ...]
	disconnect
	EOF

You can use it to run simple obdctl commands, for example:

	tests/llecho.sh
	util/obdctl --device 2 test_getattr 1000 q
	util/obdctl --device 2 test_brw 1000 w q
	tests/llmountcleanup.sh