Starting to refactor the pca model
Starting to refactor the pca model

Refactoring into two classes, one for 'instances' and one
for numpy arrays

yuxiang-zhou/menpo,patricksnape/menpo,grigorisg9gr/menpo,grigorisg9gr/menpo,menpo/menpo,menpo/menpo,grigorisg9gr/menpo,patricksnape/menpo,patricksnape/menpo,yuxiang-zhou/menpo,menpo/menpo,yuxiang-zhou/menpo