Manage noise stacks / layers / bands

[oubiwann]

Satellite data uses the term "bands" as spectrum data from satellite cameras record narrow bands of the electromagnetic spectrum as image data (and these can be viewed by rendering three or four of those bands as rgb and a in images).

Tasks:

• Decide upon term
• Add support for storing named data matrices
• Add function for retrieving names of all stored data matrices
• Add function for retrieving a stored grid by name
• Add a state API for rendering stored matrices (ascii, data, png)

[oubiwann]

The final task in that list above will be fully implemented once the data API is finalized.