multiple views on top of filters for dataset plots

[Samuel-Buteau]

dataset organization is relatively solid:

• cells have names and positions, colors
• filters have rules and and can override positions, colors

now, we would like to add multiple views into the data:

• views have names, axis labels, and types of plots (e.g. var1 vs var2), and a many_to_many with filters + overridable positions, colors