* expanding unknown env variable does not abort mtr
* have_archive, blackhole, innodb - preload the corresponding engine
* all options from .opt files get equal treatment, all are searched for special options,
not only -{master,slave}.opt as before (which ignored suite.opt and --mysqld=...)
* --plugin-load gets special treatment too - all instances are merged into one
* federated test fixed to preload federated
9bc9855c16