added a test case for it - took some creative work to figure out
how to make it happen at will
updated the manual


Docs/manual.texi:
  fixed wrong info on SLAVE_SKIP_COUNTER
  fixed wrong info in BitKeeper tree build instructions
  updated change history about bug fix
mysql-test/t/rpl_sporadic_master.test:
  tried hard to get slave confused, but failed. nevertheless, a more
  exhaustive test case does not hurt
sql/slave.cc:
  fixed mysterious offset confusion bug