Support viewing of .npz files

[exook]

In our project we store our .npy data as .npz with one array for the data and one array for the header. Would it be possible to add support for .npz?

I imagine a feature where opening a .npz file shows a tree-like structure in the GUI allowing the user to select which array to display

[csmailis]

This is in my plans, but may take some time...