Fully switch to named tables:

Kernel changes:
* Introduce ipfw_obj_tentry table entry structure to force u64 alignment.
* Support "update-on-existing-key" "add" bahavior (TEI_FLAGS_UPDATED).
* Use "subtype" field to distingush between IPv4 and IPv6 table records
  instead of previous hack.
* Add value type (vtype) field for kernel tables. Current types are
  number,ip and dscp
* Fix sets mask retrieval for old binaries
* Fix crash while using interface tables

Userland changes:
* Switch ipfw_table_handler() to use named-only tables.
* Add "table NAME create [type {cidr|iface|u32} [valtype {number|ip|dscp}] ..."
* Switch ipfw_table_handler to match_token()-based parser.
* Switch ipfw_sets_handler to use new ipfw_get_config() for mask  retrieval.
* Allow ipfw set X table ... syntax to permit using per-set table namespaces.
* Issue warning while requesting ruleset with new tables via legacy binary.
  Convert each unresolved table as table 65535 (which cannot be used normally).
* Perform s/^ipfw_// for add_table_entry, del_table_entry and flush_table since
  these are internal functions exported to keep legacy interface.
* Remove macro TABLE_SET. Operations with tables can be done in any set, the only
  thing net.inet.ip.fw.tables_sets affects is the set in which tables are looked
  up while binding them to the rule.
* Add "lookup" table functionality to permit userland entry lookups.
* Bump table dump format preserving old ABI.

Kernel size:
* Add IP_FW_TABLE_XFIND to handle "lookup" request from userland.
* Add ta_find_tentry() algorithm callbacks/handlers to support lookups.
* Fully switch to ipfw_obj_tentry for various table dumps:
  algorithms are now required to support the latest (ipfw_obj_tentry) entry
    dump format, the rest is handled by generic dump code.
  IP_FW_TABLE_XLIST opcode version bumped (0 -> 1).
* Eliminate legacy ta_dump_entry algo handler:
  dump_table_entry() converts data from current to legacy format.

Userland side:
* Add "lookup" table parameter.
* Change the way table type is guessed: call table_get_info() first,
  and check value for IPv4/IPv6 type IFF table does not exist.
* Fix table_get_list(): do more tries if supplied buffer is not enough.
* Sparate table_show_entry() from table_show_list().
* Prepare to pass other dynamic states via ipfw_dump_config()

Kernel changes:
* Change dump format for dynamic states:
  each state is now stored inside ipfw_obj_dyntlv
  last dynamic state is indicated by IPFW_DF_LAST flag
* Do not perform sooptcopyout() for !SOPT_GET requests.

Userland changes:
* Introduce foreach_state() function handler to ease work
  with different states passed by ipfw_dump_config().