text: Title: Add a new parameter to the PCADecomposition visualizer in order to plot the feature columns in the projected space (biplot)
  Body: ### Proposal
  
  Add a new parameter to the PCADecomposition class in order to have the option to plot the input columns. 
  I would like to have something like a biplot.
  
  ![image](https://user-images.githubusercontent.com/3116652/40674345-263d2d2e-633a-11e8-97f3-0634c0dee6b3.png)
  
  I can start working on the code but I would like to know if you think its a good idea.
  
  
  