BUG#49978: Replication tests don't clean up replication state at the end

Major replication test framework cleanup. This does the following:
 - Ensure that all tests clean up the replication state when they
   finish, by making check-testcase check the output of SHOW SLAVE STATUS.
   This implies:
    - Slave must not be running after test finished. This is good
      because it removes the risk for sporadic errors in subsequent
      tests when a test forgets to sync correctly.
    - Slave SQL and IO errors must be cleared when test ends. This is
      good because we will notice if a test gets an unexpected error in
      the slave threads near the end.
    - We no longer have to clean up before a test starts.
 - Ensure that all tests that wait for an error in one of the slave
   threads waits for a specific error. It is no longer possible to
   source wait_for_slave_[sql|io]_to_stop.inc when there is an error
   in one of the slave threads. This is good because:
    - If a test expects an error but there is a bug that causes
      another error to happen, or if it stops the slave thread without
      an error, then we will notice.
    - When developing tests, wait_for_*_to_[start|stop].inc will fail
      immediately if there is an error in the relevant slave thread.
      Before this patch, we had to wait for the timeout.
 - Remove duplicated and repeated code for setting up unusual replication
   topologies. Now, there is a single file that is capable of setting
   up arbitrary topologies (include/rpl_init.inc, but
   include/master-slave.inc is still available for the most common
   topology). Tests can now end with include/rpl_end.inc, which will clean
   up correctly no matter what topology is used. The topology can be
   changed with include/rpl_change_topology.inc.
 - Improved debug information when tests fail. This includes:
    - debug info is printed on all servers configured by include/rpl_init.inc
    - User can set $rpl_debug=1, which makes auxiliary replication files
      print relevant debug info.
 - Improved documentation for all auxiliary replication files. Now they
   describe purpose, usage, parameters, and side effects.
 - Many small code cleanups:
    - Made have_innodb.inc output a sensible error message.
    - Moved contents of rpl000017-slave.sh into rpl000017.test
    - Added mysqltest variables that expose the current state of
      disable_warnings/enable_warnings and friends.
    - Too many to list here: see per-file comments for details.

mysql-test/suite/rpl/r/rpl_ssl1.result

@@ -1,9 +1,5 @@
-stop slave;
-drop table if exists t1,t2,t3,t4,t5,t6,t7,t8,t9;
-reset master;
-reset slave;
-drop table if exists t1,t2,t3,t4,t5,t6,t7,t8,t9;
-start slave;
+include/master-slave.inc
+[connection master]
 grant replication slave on *.* to replssl@localhost require ssl;
 create table t1 (t int);
 stop slave;
@@ -18,23 +14,23 @@ start slave;
 select * from t1;
 t
 1
-Master_SSL_Allowed	Yes
-Master_SSL_CA_Path	
-Master_SSL_CA_File	MYSQL_TEST_DIR/std_data/cacert.pem
-Master_SSL_Cert	MYSQL_TEST_DIR/std_data/client-cert.pem
-Master_SSL_Key	MYSQL_TEST_DIR/std_data/client-key.pem
-Checking that both slave threads are running.
+Master_SSL_Allowed = 'Yes'
+Master_SSL_CA_Path = ''
+Master_SSL_CA_File = 'MYSQL_TEST_DIR/std_data/cacert.pem'
+Master_SSL_Cert = 'MYSQL_TEST_DIR/std_data/client-cert.pem'
+Master_SSL_Key = 'MYSQL_TEST_DIR/std_data/client-key.pem'
+include/check_slave_is_running.inc
 stop slave;
 change master to master_user='root',master_password='', master_ssl=0;
 start slave;
 drop user replssl@localhost;
 drop table t1;
-Master_SSL_Allowed	No
-Master_SSL_CA_Path	
-Master_SSL_CA_File	MYSQL_TEST_DIR/std_data/cacert.pem
-Master_SSL_Cert	MYSQL_TEST_DIR/std_data/client-cert.pem
-Master_SSL_Key	MYSQL_TEST_DIR/std_data/client-key.pem
-Checking that both slave threads are running.
+Master_SSL_Allowed = 'No'
+Master_SSL_CA_Path = ''
+Master_SSL_CA_File = 'MYSQL_TEST_DIR/std_data/cacert.pem'
+Master_SSL_Cert = 'MYSQL_TEST_DIR/std_data/client-cert.pem'
+Master_SSL_Key = 'MYSQL_TEST_DIR/std_data/client-key.pem'
+include/check_slave_is_running.inc
 stop slave;
 change master to
 master_host="localhost",
@@ -50,10 +46,19 @@ on slave
 select * from t1;
 t
 1
-Master_SSL_Allowed	Yes
-Master_SSL_CA_Path	
-Master_SSL_CA_File	MYSQL_TEST_DIR/std_data/cacert.pem
-Master_SSL_Cert	MYSQL_TEST_DIR/std_data/client-cert.pem
-Master_SSL_Key	MYSQL_TEST_DIR/std_data/client-key.pem
-Checking that both slave threads are running.
+Master_SSL_Allowed = 'Yes'
+Master_SSL_CA_Path = ''
+Master_SSL_CA_File = 'MYSQL_TEST_DIR/std_data/cacert.pem'
+Master_SSL_Cert = 'MYSQL_TEST_DIR/std_data/client-cert.pem'
+Master_SSL_Key = 'MYSQL_TEST_DIR/std_data/client-key.pem'
+include/check_slave_is_running.inc
 drop table t1;
+include/stop_slave.inc
+CHANGE MASTER TO
+master_host="127.0.0.1",
+master_ssl_ca ='',
+master_ssl_cert='',
+master_ssl_key='',
+master_ssl_verify_server_cert=0,
+master_ssl=0;
+include/rpl_end.inc