Monochrome grids #24
Description
Exactly the same as the existing grids but monochrome.
Considerations:
- Do we need a mode keyword/attribute or does it suffice to support single int color specs and let the mode be implied?
- Is the internal representation single digits or do we keep the the RGB tuples and make them all the same? Keeping the tuples has some advantages when it comes to the HTML repr since that's expecting a triplet.