NEURAL: Add neuralnet() as an option

[gjwgit]

Kerry would like multi-layer for the data mining course.

The neuralnet package seems to be the one.

Add ChoiceChip for nnet and neuralnet.

• https://datascienceplus.com/fitting-neural-network-in-r/
• https://www.r-bloggers.com/2010/12/r-code-example-for-neural-networks/