sql/item.cc:
  removed double_fix & already_fixed in Item_field
sql/item.h:
  added quick_fix_field() for cases when we are sure that no need full fix_field processing
  fixed neg() method for numeric constants to have the same logic as constant parser
  Item_null, Item_real, ... are constant which are fixed by creation
sql/item_cmpfunc.h:
  right fix_fields in and_conds call
sql/item_func.cc:
  changed Item_field constructor call
  fix_field emulation call
sql/item_strfunc.cc:
  correct layout
sql/item_subselect.cc:
  correct layout
  changed Item_field constructor call
sql/item_sum.cc:
  changed Item_field constructor call
sql/item_sum.h:
  changed Item_field constructor call
sql/sql_base.cc:
  fixed layout
  right fix_fields calls
sql/sql_help.cc:
  changed Item_field constructor call
sql/sql_load.cc:
  changed Item_field constructor call
sql/sql_parse.cc:
  constant changed
sql/sql_select.cc:
  fixed layout
  fix_field emulation insted of real fix_fields call
sql/sql_show.cc:
  changed Item_field constructor call
sql/sql_union.cc:
  changed Item_field constructor call
  double_fix removed
sql/sql_update.cc:
  renamed variable, fixed layout
sql/sql_yacc.yy:
  typo fixed
  fix_fields emulation calls
  hegation of numbers fixed