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.
fixed sync bugs in three test cases
added offset argument to sync_with_master to mysqltest to be able to fix sync bugs
added a test case for slave startup with existing master.info
expanded mysql-test-run.sh to be able to run pre-start shell script initializations