Now that we have primitives for parsing IPv4 ranges, let's use them to
simplify parse_iprange().

Try u_parse_ip4cidr() first. In case of failure, try u_parse_ip4range().
If any of them succeeds, verify that there aren't spurious data
following the range definition. If everything is valid, either load the
range or disable the module (if the range is 0.0.0.0/0).

The diff is a bit ugly, but the implementation should be much clearer.
Signed-off-by: NGuillaume Nault <g.nault@alphalink.fr>