Kernel changes:
* Implement proper checks for switching between global and set-aware tables
* Split IP_FW_DEL mess into the following opcodes:
  * IP_FW_XDEL (del rules matching pattern)
  * IP_FW_XMOVE (move rules matching pattern to another set)
  * IP_FW_SET_SWAP (swap between 2 sets)
  * IP_FW_SET_MOVE (move one set to another one)
  * IP_FW_SET_ENABLE (enable/disable sets)
* Add IP_FW_XZERO / IP_FW_XRESETLOG to finish IP_FW3 migration.
* Use unified ipfw_range_tlv as range description for all of the above.
* Check dynamic states IFF there was non-zero number of deleted dyn rules,
* Del relevant dynamic states with singe traversal instead of per-rule one.

Userland changes:
* Switch ipfw(8) to use new opcodes.
Since all of base IP_FW opcodes has been converted to IP_FW3,
switch default sopt handler to ipfw_clt3.
Add some comments for ipfw_get_sopt* api.
Remove IP_FW_TABLES_XGETSIZE opcode.
It is superseded by IP_FW_TABLES_XLIST.
* Add IP_FW_TABLE_XMODIFY opcode
* Since there seems to be lack of consensus on strict value typing,
  remove non-default value types. Use userland-only "value format type"
  to print values.

Kernel changes:
* Add IP_FW_XMODIFY to permit table run-time modifications.
  Currently we support changing limit and value format type.

Userland changes:
* Support IP_FW_XMODIFY opcode.
* Support specifying value format type (ftype) in tablble create/modify req
* Fine-print value type/value format type.
* Switch tablearg value from 65535 to 0.
* Use u16 table kidx instead of integer on for iface opcode.
* Provide compability layer for old clients.
Partially revert previous commit:
"0" value is perfectly valid for O_SETFIB and O_SETDSCP,
  so tablearg remains to be 655535 for now.
Kernel changes:
* Fix buffer calculation for table dumps
* Fix IPv6 radix entiries addition broken in r269371.

Userland changes:
* Fix bug in retrieving statric ruleset
* Fix several bugs in retrieving table list
* Use 2 32-bits field inside rule instead of 2 pointer to save skipto state.
* Introduce ipfw_reap_add() to unify unlinking rules/adding it to reap queue
* Unbreak FreeBSD7 export format.