Addendum to previous: remove debug traces
NeuralNet propogation
    * Layer.hs
        * Flipped around propL code to be a bit neater
    * Newtypes.hs
        * Added Input vector newtype
        * Added Activations type alias
    * Dimensions.hs
        * Added CheckDims helper function
    * NeuralNet.hs
        * Added basic forward propogation algorithm
Single-example backprop added
    * Filter.hs
        * Corrected FilterDeriv to take ErrorSignal as argument
    * Layer.hs
        * Moved propL to Propogation.hs
    * NeuralNet.hs
        * Moved propogate to Propogation.hs
    * Newtypes.hs
        * Added Update matrix wrapper, helper functions for
          transpose and outer product
    * Propogation.hs
        * Moved forward propogation methods here
        * Added backpropL and backpropogate
Small refactor of NNet and misc fixes
    * nunavut.cabal
        * removed mystery unused transformers import
    * NeuralNet.hs
        * removed FFNet definition/lenses/instances
    * NeuralNet/Internal.hs
        * moved definitions/lenses here for internal import
    * Newtypes.hs
        * Couple extra instances for ErrorSignal
    * Propogation.hs
        * Added dimension check of activations parameter to backpropL
Testing refactor and barebones backprop tests
    * FilterSpec
        * Fixed test to reflect previous filterDeriv signature change
    * LayerSpec
        * Moved propL tests to PropogationSpec
    * Arbitrary
        * New instances to support propogation tests
    * TestUtils
        * isTotal methods for 2- and 3-arg functions
    * PropogationSpec
        * Some very limited tests for backpropogation.
        * Most relevant properties are only defined for expectations
          on these methods, so need some more stuff implemented before
          I can test.