Conditional Random Fields

[Ayushk4]

• Viterbi Decode
• Supports for training with Flux Layers
• Documentation
• Tests
• Extended example over the Flux layers

[MikeInnes]

Seems fine to me code style wise; @aviks don't know if you want any deeper look over this, but it's not a model I'm really familiar with.

Could probably use some tests / a usage demo but you have that listed. If this is something that's designed to be trained by users, rather than classifying things out of the box, maybe there's a case for just having it in Flux itself?

You might want to look at Flux.@treelike so that this model can be moved the the GPU and such.

[Ayushk4]

@aviks Please review this PR.

[aviks]

I'm merging this here for now. It may be worth moving to Flux, but I don't want to make that a blocker for further work. Ayush, you may want to make a PR to Flux at some point with this model, but it's not urgent.