- implement read ahead during disk data scan


storage/ndb/src/kernel/blocks/dbtup/Dbtup.hpp:
  maximum read ahead
storage/ndb/src/kernel/blocks/dbtup/DbtupGen.cpp:
  maximum read ahead should not be larger than page buffer size
  maximum aslo set to 32 pages
storage/ndb/src/kernel/blocks/dbtup/DbtupScan.cpp:
  read ahead for disk data scan
storage/ndb/src/kernel/blocks/pgman.cpp:
  set higher max_io_waits for read ahead
  round off upwards in page_buffer size
storage/ndb/src/kernel/vm/SimulatedBlock.cpp:
  add null callback to be used for read ahead (no callback needed)
storage/ndb/src/kernel/vm/SimulatedBlock.hpp:
  add null callback to be used for read ahead (no callback needed)
storage/ndb/src/ndbapi/TransporterFacade.cpp:
  remove the debug trace, not needed any more
storage/ndb/test/tools/hugoFill.cpp:
  allow setting database in hugoFill