MFC: sync ipfw2 (kernel, userland, manpage) with the version in -current.
Among other things, this includes the following:

+ pass to the preprocessor all command-line options after -p

(except the last one, the ruleset file)

+ add the "verrevpath" option
+ support strong alignment architectures such as alpha and sparc64;
+ support multiple values and ranges for "iplen", "ipttl", "ipid" options.
+ support range notations such as 1.2.3.4/24{5,6,7,10-20,60-90}

for sets of IP addresses

The changes (also those in sys/netinet/ip_dummynet.c) are all
IPFW2-specific, which is entirely optional in RELENG_4 so there
are no ABI issues for those using the standard ipfw[1].

Note, however, that ipfw2 users MUST REBUILD /sbin/ipfw
together with the new kernel.