daemon: compare_device_names: Fix typo in this function.

This would have broken the function if we were comparing mixed
/dev/sda and /dev/ubda (ie different length) strings.  Which we never
normally do, luckily.
launch: direct: Print \n after printing qemu command line.

This makes it easier to see error messages printed by qemu.
docs: Clearer documentation for User-Mode Linux.

This updates commit 858d6e7176d7b18bc29c8503bbc2887a3b74a272.
tests: c-api: Fix device name comparison when using User-Mode Linux.

This updates commit 858d6e7176d7b18bc29c8503bbc2887a3b74a272.