Allow kernel options such as p2v.o=libvirt to override internal
defaults, even for GUI configuration.
The main change is to split up the kernel conversion into two steps:
reading the kernel command line configuration, and performing the
conversion. The kernel command line can then be read by the main
program and used to initialize the config structure for either kernel
conversion or GUI conversion.
A small adjustment is required in the test because p2v.pre no longer
runs before kernel command line parsing. (The aim is to have
p2v.pre/post/fail still only run when doing a kernel conversion, not
in the GUI case.)
fb74a275c1