Fixes when using column privileges
Manual updates


Docs/manual.texi:
  Comments from MySQL training + distinct optimization
extra/my_print_defaults.c:
  Added --defaults-extra-file
include/my_sys.h:
  Added --defaults-extra-file
mysys/default.c:
  Added --defaults-extra-file
sql/sql_acl.cc:
  Tables with only column privileges didn't show up in SHOW GRANTS or SHOW TABLES
sql/sql_select.cc:
  DISTINCT optimization
sql/sql_select.h:
  DISTINCT optimization
BitKeeper/etc/logging_ok:
  Logging to logging@openlogging.org accepted