This patch teaches testutil how to read multi-line input files with
backspace-newline line continuation markers.
The patch also breaks up all the single-line arguments test input files into
multi-line files with lines shorter than 80 characters.
Commit febc591683 introduced -vga none in
case no video card is included in domain XML. However, old qemu
versions do not support this and such domain cannot be successfully
started.
