main: fix issue with -H switch not expanding %default

Signed-off-by: Jan Pokorný <jpokorny@redhat.com>
main: reorder some options in help msg, --dist is non-expert

...as it is anticipated it may be quite frequented (conversion
executed on the old machine/distro)

Signed-off-by: Jan Pokorný <jpokorny@redhat.com>