Fix bug #3443, better foreign key error messsages.

innobase/dict/dict0dict.c:
  Add 'add_newline' parameter to dict_print_info_on_foreign_key_in_create_format.
innobase/include/dict0dict.h:
  Add 'add_newline' parameter to dict_print_info_on_foreign_key_in_create_format.
innobase/include/os0file.h:
  Add os_file_read_string.
innobase/include/trx0trx.h:
  Add trx_set_detailed_error and trx_set_detailed_error_from_file functions
  and a detailed_error field to trx_struct.
innobase/include/ut0mem.h:
  Add ut_strlcpy.
innobase/os/os0file.c:
  Add os_file_read_string.
innobase/row/row0ins.c:
  Add row_ins_set_detailed function and call it when needed.
  
  Adapt to changes in dict_print_info_on_foreign_key_in_create_format.
innobase/trx/trx0trx.c:
  Add trx_set_detailed_error and trx_set_detailed_error_from_file.
  
  Clear trx->detailed_error in trx_create.
innobase/ut/ut0mem.c:
  Add ut_strlcpy.
mysql-test/r/innodb.result:
  Add new tests, adapt existing ones whose output was changed.
mysql-test/t/innodb.test:
  Add new tests, adapt existing ones whose output was changed.
sql/ha_innodb.cc:
  Add get_error_message.
  
  Clear trx->detailed_error in start_stmt and external_lock.
sql/ha_innodb.h:
  Add get_error_message.
sql/handler.cc:
  Add special case code in print_error for HA_ERR_ROW_IS_REFERENCED and
  HA_ERR_NO_REFERENCED_ROW.
  
  Change SETMSG to point to new error messages.
sql/share/errmsg.txt:
  Add ER_ROW_IS_REFERENCED_2 and ER_NO_REFERENCED_ROW_2.

sql/ha_innodb.h

@@ -174,6 +174,8 @@ class ha_innobase: public handler
 	void init_table_handle_for_HANDLER(); 
 	ulonglong get_auto_increment();
 	int reset_auto_increment(ulonglong value);
+
+	virtual bool get_error_message(int error, String *buf);
 	
         uint8 table_cache_type() { return HA_CACHE_TBL_ASKTRANSACT; }
         /*