Maintenance release

[0.6.6] - Aug 12, 2022

Compatibility

• Require GPyTorch >= 1.8.1 (#1347).

New Features

• Support batched models in RandomFourierFeatures (#1336).
• Add a skip_expand option to AppendFeatures (#1344).

Other Changes

• Allow qProbabilityOfImprovement to use batch-shaped best_f (#1324).
• Make optimize_acqf re-attempt failed optimization runs and handle optimization
  errors in optimize_acqf and gen_candidates_scipy better (#1325).
• Reduce memory overhead in MARS.set_baseline_Y (#1346).

Bug Fixes

• Fix bug where outcome_transform was ignored for ModelListGP.fantasize (#1338).
• Fix bug causing get_polytope_samples to sample incorrectly when variables
  live in multiple dimensions (#1341).

Documentation

• Add more descriptive docstrings for models (#1327, #1328, #1329, #1330) and for other
  classes (#1313).
• Expanded on the model documentation at botorch.org/docs/models (#1337).