Some simple optimizations


Docs/manual.texi:
  Updted how binary log works
mysql-test/mysql-test-run.sh:
  Added usage of --port to mysqltest
mysql-test/r/func_test.result:
  Moved test of datetime comparison to func_time
mysql-test/r/func_time.result:
  New test
mysql-test/t/func_test.test:
  Moved test of datetime comparison to func_time
mysql-test/t/func_time.test:
  Test of DATE BETWEEN TIMESTAMPS
sql/field.h:
  Removed wrong patch
sql/item_cmpfunc.cc:
  Removed wrong patch
  (Need to be fixed by taking into account all arguments to between)
sql/lock.cc:
  Removed call to current_thd
sql/set_var.cc:
  Don't show 'socket' variable if sockets are not used
sql/sql_base.cc:
  Simple optimisation