iterators creation interface added to handlerton


sql/ha_berkeley.cc:
  added new methods
sql/ha_federated.cc:
  added new methods
sql/ha_heap.cc:
  added new methods
sql/ha_innodb.cc:
  added new methods
sql/ha_myisam.cc:
  added new methods
sql/ha_myisammrg.cc:
  added new methods
sql/ha_ndbcluster.cc:
  added new methods
sql/ha_partition.cc:
  added new methods
sql/handler.cc:
  added new methods
  spelling fixed
  examples of functions for new interface added
sql/handler.h:
  transaction logs management interface added
  general iterator creatioin interface added
sql/log.cc:
  added new methods
storage/archive/ha_archive.cc:
  added new methods
storage/blackhole/ha_blackhole.cc:
  added new methods
storage/csv/ha_tina.cc:
  added new methods
storage/example/ha_example.cc:
  added new methods