mysqld >=4.1.3 will however understand shutdown requests sent by clients <4.1.3.
And mysqld <4.1.3 will understand shutdown requests sent by clients >=4.1.3
(it will ignore the level). Those shutdown level are just PLACEHOLDERS now.
So this change is just to make the 4.1 API suitable before it is frozen. Later
we will actually implement the shutdown levels.


VC++Files/winmysqladmin/main.cpp:
  2nd argument to mysql_shutdown()
VC++Files/winmysqladmin/mysql.h:
  2nd argument to mysql_shutdown()
VC++Files/winmysqladmin/mysql_com.h:
  Several types of shutdown now.
include/mysql_com.h:
  SHUTDOWN_DEFAULT is now 0 instead of 255, this saves one test in sql_parse.cc
libmysql/libmysql.c:
  correcting mistake (how come that my tests still all worked with this? - should recheck, for curiosity).
sql/sql_parse.cc:
  with SHUTDOWN_DEFAULT==0, no need for testing packet_length.