generalization of mtr to support suite.pm extensions:

* no automatic --loose-skip-innodb added by mtr based on the test name.
  instead loose-skip-innodb is now in the default_mysqld.cnf
* have_innodb_plugin.inc is changed to give a verbose "skip" message
  (instead of "require: true")
* My::Suite class. It's support in mtr, and everywhere
* support for suite.pm
* when sorting tests, take combinations into account
* support for SUITENAME_COMBINATIONS
* no special treatment for innodb_plugin in mtr_cases.pm
* two special pre-created config groups: ENV and OPT
* allow option names to start from #
* allow magic option to have an argument
* remove dead code
* fix @-substitution to works as expected
* new processes take the value of $opt_verbose automatically, no need to pass it to a constructor
* innodb_plugin suite uses suite.pm and combinations file to test as much as possible
  (innodb plugin, xtradb plugin, xtradb static - whatever available)
* besides test-master.opt and test-slave.opt a test.opt file is also
  loaded, both for master and slave
* .opt files for all included files are loaded too
* progress report in the xterm titlebar

mysql-test/suite/innodb_plugin/t/innodb_bug53674-master.opt

@@ -1 +1 @@
---log-bin --innodb-locks-unsafe-for-binlog --binlog-format=mixed
+--log-bin=master-bin --loose-innodb-locks-unsafe-for-binlog --binlog-format=mixed