make it possible to change feedback plugin wait intervals
* only in debug builds
* and force the feedback report to be ignored
update the test to use this feature
The test restarts the server and expects that the feedback plugin
will send a report on shutdown, and will write about it in the error
log. But the server is only given 10 sec to shut down properly,
which is not always enough.
Added a parameter to restart_mysqld.inc, and set it to a bigger
value in feedback_plugin_send
2. dialog plugin now always returns mysql->password if non-empty and the first question is of password type
3. split get_tty_password into get_tty_password_buff and strdup.
4. dialog plugin now uses get_tty_password by default
5. dialog.test
6. moved small tests of individual plugins into a dedicated suite
