✨ Toy Machines

[hayesall]

This adds a "machines" dataset based closely on the one described in the ACE Data Mining User Guide.

• Changed not_replaceable to irreplaceable
• Split into train/test folds (this would be a trivial case to split into multiple folds, possibly consider that sometime in the future as an introduction to multiclass classification or cross validation).

I made machines 13, 14, and 15 the test examples, meaning one example each of sendback, ok, fix exists in the test data.