v0.6.0

Added

• ml/losses.WeightedCrossEntropy()
• ml/losses.FocalLoss()
• ml/losses.WeightedFocalLoss()
• nlp/sequencelabeler.LoadModel() (it replaces Load() and LoadEmbeddings())
• nlp/charlm.LoadModel()
• nlp/transformers/bert.Model.PredictMLM()
• nlp/transformers/bart/tasks package
• nlp/transformers/bert.Model.Vectorize()
• ml/ag.Graph.Nodes() and ml/ag.Nodes()
• ml/nn.Model.Close()
• ml/nn.ReifyForTraining() and ml/nn.ReifyForInference()
• ml/ag.Graph.Backward() now panics if it is executed with nodes belonging to
  different graphs.
• The new ml/graphviz package allows exporting a Graph to Graphviz
  DOT format. To make it possible,
  we introduced a new go-mod dependency gographviz.
• A custom name can be optionally set to a Graph's Variables. This can be
  useful for debugging purposes and visual graph representation.
  You can now use Graph.NewVariableWithName() and Graph.NewScalarWithName()
  to create named Variables, and get the name of a Variable with
  Variable.Name().

Changed

• All UnaryElementwise functions provided by the package ag/fn have been
  promoted to separate dedicated structs. This improves debuggability and you
  can get appropriate function names when using reflection. Here is the full
  list of the modified functions: Tan, Tanh, Sigmoid, HardSigmoid,
  HardTanh, ReLU, Softsign, Cos, Sin, Exp, Log, Neg,
  Reciprocal, Abs, Mish, GELU, Sqrt, Swish.
  For the same reason, a dedicated Square function is introduced, replacing
  Prod with both operands set to the same value.
• ml/ag types Operator, Variable, Wrapper are now public.
• ml/nn.Reify() now expects a Graph and a Processing Mode arguments
  instead of a Context object (removed).
• ml/nn.BaseModel has been modified, replacing the field Ctx Context with
  a direct reference to the model's Graph and the Processing Mode (fields G
  and ProcessingMode).
• Refactoring server implementation of nlp/sequencelabeler,
  nlp/transformers/bert, and nlp/transformers/bart.
• Upgrade various dependencies.
• Regenerate protocol buffers files (with protoc-gen-go v1.26.0 and
  protoc v3.16.0).

Removed

• nlp/sequencelabeler.Load() and LoadEmbeddings() (now replaced by
  nlp/sequencelabeler.LoadModel())
• ml/nn.Context (see related changes on Reify() and BaseModel)