Make the slave options --replicate-* dynamic variables so that these
options can be changed dynamically while the server is running,
which enables users to modify replication filtering rules without
having to stop and restart the server.

This is accomplished by just requiring that the slave threads are
stopped when these options are set dynamically. Since filtering
rules are only used by the SQL slave thread, setting them while the
thread is not running avoids the need for locking.