- Allow test case names to be specied in various different ways


mysql-test/lib/mtr_cases.pl:
  Allow test name to be specified in all sorts of ways:
  mysql-test-run alias
  mysql-test-run alias.test
  mysql-test-run main.alias
  mysql-test-run main.alias.test
  mysql-test-run t/alias
  mysql-test-run t/alias.test