Unable to pass extra args with spaces

[mikedld]

In some cases, as with e.g. -smbios, it's useful to be able to pass values containing spaces. I didn't succeed in trying to achieve that though (with v3.3.0):

• using single quotes leads to nemu errors (I suspect due to unsufficient SQL query escaping)
• using double quotes or backslash escaping leads to qemu errors (due to invalid command line)

This appears to be because parsing of extra args is quite simplistic, using strtok_r() with " " (space) as separator.