* When converting a tensor to a variable, clone if the tensor is already a variable.
* Add a test to ensure training a batch norm works with VarMaps
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Co-authored-by: Jeffrey Dallatezza <jeffreydallatezza@Jeffreys-Laptop.local>
* Add the nn::optim and some conversion traits.
* Add the backward_step function for SGD.
* Get the SGD optimizer to work and add a test.
* Make the test slighly simpler.
* Move the variable creation to the variable module.
* Make it possible to set a variable.
* Add some basic gradient descent test.
* Get the gradient descent test to work.