- Merge with MariaDB 5.3 -main

- Remove deadcode
- Improve comments 
- Do small several small TODOs

- Item_in_subselect::init_left_expr_cache() should not try to 
  guess whether the left expression is accessed "over the grouping operation"
  (i.e. the subselect is evaluated after the grouping while the left_expr is
   an Item_ref that wraps an expression from before the grouping). Instead, 
  let new_Cached_item not to try accessing item->real_item() when creating 
  left expr cache.

join cache module.
Without these calls SELECTs over tables with virtual columns
that used join cache could return wrong results. This could
be seen with the test case added into vcol_misc.test 

  field->pack_length() bytes.

5.3 had 

 handler::index_only_read_time(uint keynr, double records)

while 5.2 got:

 handler::keyread_read_time(uint index, uint ranges, ha_rows rows)

which causes floor()'ing of rows parameter, which makes all further costs different.

- fix a bug in LooseScan strategy execution code (exposed by changing costs/QEP)
- Do set join_tab->sorted=TRUE for JOIN_TABs that use LooseScan (partitioning 
   handler cares about "sorted" parameter of h->index_init() call)

- Remove garbage comments
- fix a bug in join_tab_cmp

of two query plans with identical costs.

- Unify EXPLAIN printout for <subqueryN> tables with regular tables
- Update test results for <subqueryN> tables:
  s/unique_key/distinct_key/g
  s/1.0/100.0/ for "filtered" column

- Fix test failures: do not use make_cond_after_sjm()'s result in case
  of merged SJ-Materialization lookup
- Update test results

MWL#90: Subqueries: Inside-out execution for non-semijoin materialized subqueries that are AND-parts of the WHERE
- Address feedback
- Code cleanup (not finished)

create st_maria_plugin declarations of new xtradb I_S tables

- Make join buffering take into account that join_tabs are not a 
  single linear array anymore
- Remove outer join + SJ-Materialization crash (OJ+SJ the processing
  is most likely still incorrect)

* remove handler::index_read_last()
* create handler::keyread_read_time() (was get_index_only_read_time() in opt_range.cc)
* ha_show_status() allows engine's show_status() to fail
* remove HTON_FLUSH_AFTER_RENAME
* fix key_cmp_if_same() to work for floats and doubles
* set table->status in the server, don't force engines to do it
* increment status vars in the server, don't force engines to do it

mysql-test/r/status_user.result:
  correct test results - innodb was wrongly counting internal
  index searches as handler_read_* calls.
sql/ha_partition.cc:
  compensate for handler incrementing status counters -
  we want to count only calls to underlying engines
sql/handler.h:
  inline methods moved to sql_class.h
sql/key.cc:
  simplify the check
sql/opt_range.cc:
  move get_index_only_read_time to the handler class
sql/sp.cc:
  don't use a key that's stored in the record buffer -
  the engine can overwrite the buffer with anything, destroying the key
sql/sql_class.h:
  inline handler methods that need to see THD and TABLE definitions
sql/sql_select.cc:
  no ha_index_read_last_map anymore
sql/sql_table.cc:
  remove HTON_FLUSH_AFTER_RENAME
sql/table.cc:
  set HA_CAN_MEMCMP as appropriate
sql/tztime.cc:
  don't use a key that's stored in the record buffer -
  the engine can overwrite the buffer with anything, destroying the key
storage/myisam/ha_myisam.cc:
  engines don't need to update table->status or use ha_statistic_increment anymore
storage/myisam/ha_myisam.h:
  index_read_last_map is no more

- Make join buffering code to take into account that JOIN_TABs are not a 
  linear array anymore.

- First code, needs cleanup.

mysql-test/suite/pbxt/r/mysqlshow.result:
  update the forgotten test results
sql/table.cc:
  add defensive asserts.
  fix the code that didn't in MySQL > 5.2.0 with frm's created before 5.1.10