first pull, merge,test, and get it to work.

The main change is the new replication code - now we have two slave threads
SQL thread and I/O thread. I have also re-written a lot of the code to 
prepare for multi-master implementation. 

I also documented IO_CACHE quite extensively and to some extend, THD class.


Makefile.am:
  moved tags target script into a separate file
include/my_sys.h:
  fixes in IO_CACHE for SEQ_READ_APPEND + some documentation
libmysqld/lib_sql.cc:
  updated replication locks, but now I see I did it wrong and it won't compile. Will fix
  before the push.
mysql-test/r/rpl000014.result:
  test result update
mysql-test/r/rpl000015.result:
  test result update
mysql-test/r/rpl000016.result:
  test result update
mysql-test/r/rpl_log.result:
  test result update
mysql-test/t/rpl000016-slave.sh:
  remove relay logs
mysql-test/t/rpl000017-slave.sh:
  remove relay logs
mysql-test/t/rpl_log.test:
  updated test
mysys/mf_iocache.c:
  IO_CACHE updates to make replication work
mysys/mf_iocache2.c:
  IO_CACHE update to make replication work
mysys/thr_mutex.c:
  cosmetic change
sql/item_func.cc:
  new replication code
sql/lex.h:
  new replication
sql/log.cc:
  new replication
sql/log_event.cc:
  new replication
sql/log_event.h:
  new replication
sql/mini_client.cc:
  new replication
sql/mini_client.h:
  new replication
sql/mysql_priv.h:
  new replication
sql/mysqld.cc:
  new replication
sql/repl_failsafe.cc:
  new replication
sql/slave.cc:
  new replication
sql/slave.h:
  new replication
sql/sql_class.cc:
  new replication
sql/sql_class.h:
  new replication
sql/sql_lex.h:
  new replication
sql/sql_parse.cc:
  new replication
sql/sql_repl.cc:
  new replication
sql/sql_repl.h:
  new replication
sql/sql_show.cc:
  new replication
sql/sql_yacc.yy:
  new replication
sql/stacktrace.c:
  more robust stack tracing
sql/structs.h:
  new replication code
BitKeeper/etc/ignore:
  Added mysql-test/r/rpl000002.eval mysql-test/r/rpl000014.eval mysql-test/r/rpl000015.eval mysql-test/r/rpl000016.eval mysql-test/r/slave-running.eval mysql-test/r/slave-stopped.eval to the ignore list