Add tests

[kwinkunks]

Probably using jest.

Not too bothered about testing the entire application, but it would be smart to at least test the NN functions:

export let activations: {[key: string]: nn.ActivationFunction} = {
  "relu": nn.Activations.RELU,
  "leakyrelu": nn.Activations.LeakyRELU,
  "elu": nn.Activations.ELU,
  "tanh": nn.Activations.TANH,
  "sigmoid": nn.Activations.SIGMOID,
  "swish": nn.Activations.SWISH,
  "mish": nn.Activations.MISH,
  "softplus": nn.Activations.SOFTPLUS,
  "gelu": nn.Activations.GELU,
  "linear": nn.Activations.LINEAR,
  "bent": nn.Activations.BENT_IDENTITY
};

/** A map between names and regularization functions. */
export let regularizations: {[key: string]: nn.RegularizationFunction} = {
  "none": null,
  "L1": nn.Regularizations.L1,
  "L2": nn.Regularizations.L2,
  "elastic net": nn.Regularizations.ElasticNet,
  "huber": nn.Regularizations.Huber
};

/** A map between names and eval functions. */
export let evals: {[key: string]: nn.EvalFunction} = {
  "f1": nn.Evals.F1,
  "mcc": nn.Evals.MATTHEWS_CORR_COEFF,
  "r2": nn.Evals.R2,
  "rmse": nn.Evals.RMSE
};

/** A map between names and loss functions. */
export let errors: {[key: string]: nn.ErrorFunction} = {
  "square": nn.Errors.SQUARE,
  "absolute": nn.Errors.ABS,
  "hinge": nn.Errors.HINGE,
  "squared hinge": nn.Errors.SQUARED_HINGE,
  "huber": nn.Errors.HUBER,
  "modified huber": nn.Errors.MODIFIED_HUBER,
  "cross entropy": nn.Errors.BINARY_CROSS_ENTROPY,
  "exponential": nn.Errors.EXPONENTIAL,
  "poisson": nn.Errors.POISSON,
  "epsilon insensitive": nn.Errors.EPSILON_INSENSITIVE
};