mlr3 0.1.2

• Deprecated support of automatically creating objects from strings.
  Instead, mlr3 provides the following helper functions intended to ease the
  creation of objects stored in dictionaries:
  tsk(), tgen(), lrn(), rsmp(), msr().

• BenchmarkResult now ensures that the stored ResampleResults are in a
  persistent order. Thus, ResampleResults can now be addressed by their
  position instead of their hash.

• New field BenchmarkResult$n_resample_results.

• New field BenchmarkResult$hashes.

• New method Task$rename().

• New S3 generic as_benchmark_result().

• Renamed Generator to TaskGenerator.

• Removed the control object mlr_control().

• Removed ResampleResult$combine().

• Removed BenchmarkResult$best().