Added dark and bright modes to Zx Spectrum

[robin-raymond]

Added dark and bright modes to Zx Spectrum

The Zx spectrum has interesting palette restrictions. Each pixel can choose from the bright part of the palette or the dark part of the palette in a cell, but no cell can choose both bright and dark at the same time.

The previous code selected from palette that was bright only and then forced a bright mode. The new logic understands the possible dark vs light choice and then chooses the appropriate dark/light choice per cell.

New options also exist to force a light or dark mode if the user has a preference for one palette or the other (for whatever reasons they might have).

Changes to the code:

• the spectrum palette was expanded to include dark and bright
• systems were added to allow choices between the dark and bright
• the cell exporter was made more generic to allow x/y mapping to param/cell to be generic enough to handle the oddity that is the Zx Spectrum memory layout
• the Zx canvas logic was made to understand the dark vs bright selection choice

Related to https://github.com/sehugg/dithertron/issues/22

[robin-raymond]

I have no idea why this is failing. I don't see an obvious error. Maybe it needs to be retried?

[robin-raymond]

I tried kicking it off again, but it just failed...

I merged and now my branch does this:

npm run build

> dithertron@1.2.1 build
> make copylibs && npm run esbuild-worker && npm run esbuild-ui

The syntax of the command is incorrect.
make: *** [Makefile:11: copylibs] Error 1

I don't want to mess with that stuff so if you can help that would be appreciated. Thanks!

[robin-raymond]

Ok, the make file issue for me is because I'm running under windows, not linux, but it doesn't explain the check failure.