sql/handler.cc:
  do not delete the table in the "unkonwn" handler (makes no sense anyway)
sql/handler.h:
  more HA_CREATE_USED flags
sql/sql_lex.h:
  more ALTER_ flags, no alter_info->is_simple anymore
sql/sql_parse.cc:
  no alter_info->is_simple anymore
sql/sql_table.cc:
  do not rename the table in the "unkonwn" handler (makes no sense anyway)
  smarter ALTER TABLE - don't copy the table if only comment or default values are changed
sql/sql_yacc.yy:
  specify what ALTER is todo with flags, not alter_info->is_simple
sql/unireg.cc:
  create frm only (but not in the handler) if requested