Create a Multilayer tutorial/notebook (data visualization-focused)

[multinetlab]

The idea is to improve how we visualize the data.

1. raster plots and whatever else gives us spatial info
2. histograms

obs. let's try to make the raster with brain areas organization (e.g. cortical areas, etc).
Also consider the individual vs mean raster plot.

[eduardacenteno]

@fnobregasantos and @lcbreedt, is this a project still or should I remove it from our plans?